Makita (Australia) Pty Ltd v Sprowles

PRIESTLEY JA : All the relevant facts and materials are set out in the reasons of Powell and Heydon JJA. I arrive at the same conclusion as they do, but by a shorter way.

The plaintiff’s description of her fall was brief and uninformative. As the trial judge said in his reasons: “ In her evidence the plaintiff merely said that her foot went out from underneath her ”.

The trial judge’s conclusion that the plaintiff’s fall was because of the slipperiness of a tread on the stairs rather than because she simply lost her footing was based on Professor Morton’s expert opinion that the stairs were slippery. It seems clear that without Professor Morton’s opinion, the trial judge would not have found the plaintiff fell because of the slipperiness of the stairs.

In my view the trial judge erred in accepting Professor Morton’s opinion of slipperiness. This opinion contradicted uncontradictable facts that showed that the stairs were not slippery in any ordinary meaning of the word. For the stairs (or any single step) to be slippery in a sense relevant for the present case, they (or it) must in my opinion have the characteristic that persons walking on them (or it) with ordinary care will, from time to time, slip.

The plaintiff began work with the defendant on 16 January 1984. She suffered her fall on 30 June 1986. She walked up and down the stairs every working day. There were more than fourteen steps in the stairway. On the basis of a five day working week and four weeks annual holidays this means that she walked down over the step on which she fell at least 575 times. Absences may have reduced this number. Call it 500 and the point still seems to be irresistible. (Since all the steps seem to have been of the same composition, the relevant figure is probably at least 7000.) The plaintiff fell once. She gave no evidence that she had ever slipped. There was no evidence that any one else ever slipped. One fall in more than 500 uses of a step (or 7000 uses of all the steps in a stairway) is not evidence that the step (or the steps in the stairway) is (or are) slippery in any relevant use of the word. It is evidence of the opposite. The only conclusion, in my opinion, is that Professor Morton’s opinion about the slipperiness of the steps in the stairway was so clearly wrong that even his impressive qualifications could not rescue it.

Once I reach this conclusion, it seems to me to follow that the judgment in this case should be set aside, and in its place judgment entered for the defendant.

I agree with the orders proposed by Heydon JA.

POWELL JA: I have read in draft the Judgment which has been prepared by Heydon JA. Since the facts which are said to have given rise to these proceedings and which gave rise to this appeal are recorded in some detail in his Honour’s Judgment, it is not necessary that I repeat them here.

Reduced to its most simple form, the case which the Respondent sought to make at trial was that the Appellant had failed to fulfil its duty of care to her in that it failed to take reasonable care to provide a safe means of access from the roof-top car park to the office where the Respondent worked (RAB 72). The manner in which the Respondent set about attempting to establish that case was to lead evidence to establish, first, that the stairs were slippery, and, second, that there were reasonable practical steps which the Appellant could have taken to obviate the risk of injury to its employees arising from that fact, but which steps the Appellant had not taken.

It seems to me, however, that the Respondent faced three, not inconsiderable, difficulties in her attempts to establish that case, they being: a. the evidence of the lay witnesses – including that of the Respondent herself (Black AB 40) – appeared to demonstrate that, notwithstanding that those of the Appellant’s staff who drove to work were, on a daily basis, accustomed to park on the roof-top car park and use the stairs as a means of access to the Appellant’s premises on the first and ground floors of the building, the only occasion upon which any of those employees was said to have slipped when doing so was that of which the Respondent complained – that occasion being 2½ years after the Respondent commenced to work for the Appellant and almost 9 years before she left its employ – a fact which cast more than a shadow of doubt over any assertion that the stairs were slippery and that the Respondent ought to have taken steps to obviate the risk of injury to its employees arising from that fact; b. neither the Australian Standard for surface friction of floors (AS 3661.1:1993) – which, in any event, had not been adopted at the time of the incident of which the Respondent complained – nor the British standard for steps and stairs (BS 5395) – was tendered in evidence, so that it is not possible to know whether what Professor Morton wrote in his report (Blue AB 1-6-107) – upon which the Respondent relied – as to their contents was either accurate or complete, and still less is it possible to know whether the conclusions as to the slipperiness of the steps which Professor Morton sought to base upon his tests – which tests, in any event, do not appear to have been carried out in accordance with the Australian Standard method (Blue AB 111) - can be seen to have been validated; c. far from it being seen that those conclusions have been validated, it seems to me, for the reasons to which I will now turn, that the process by which Professor Morton reached those conclusions reveals internal inconsistencies and confusion such that his conclusions are of no real value.

In his report, Professor Morton wrote (inter alia) as follows (Blue AB 106): “ 3.6 Standards for frictional grip and safety Until recently there have been no Australian or other national standards for surface friction of floors or footwear. An Australian Standard (AS 3661.1:1993) was issued in October 1993. This document sets a minimum value of 0.4 for the dynamic friction, dry or wet, when tested against a certain standard simulated shoe sole (4S) hard rubber material for a floor to be considered as slip-resistant. It should be noted however that a floor satisfying this requirement is not necessarily safe, and particularly not for use by other types of footwear or under other conditions. A second part of the Standard (AS 3661.2:1994) dealing with methods of reduction of slipping hazards has been issued (February 1994). British Standard BS 5395 for steps and stairs also indicates that a dynamic coefficient below 0.4 is unsatisfactory. Whilst there are no universally agreed standards for floor friction it is usually accepted that dynamic friction coefficients below 0.4 are unsafe whereas above 0.5 they are safe.”

That passage seems to me to invite the following comments: a. at the time of the incident of which the Respondent complained there was no Australian Standard for surface friction of floors; b. if the passage accurately, and completely, records the relevant parts of AS 3661.1:1993, what is there established is a standard for floors, not a standard for floors and various types of footwear; c. that standard is a single standard, which, when met, indicates that the relevant floor is to be regarded as slip resistant; d. the test for determining whether or not, in any particular case, the standard has been met involves the use of a simulated shoe sole of a standard (4S) hard rubber material, not the use of a variety of materials; e. if this be not so, then, given the wide variety of materials of which the soles of shoes may be composed, it would be virtually impossible to know whether, in any particular case, the standard has been met and the floor in question is to be regarded as slip resistant.

In his report, Professor Morton also wrote (Blue AB 110-111): “ 4.4.2 Measurement methods I made measurements of coefficients of friction on the treads following procedures based on the standard of the American Society for Testing Materials, method D1894 modified as necessary for testing floors ‘in the field’. For this purpose I used a number of test sliders of typical shoe-sole materials and the 4S rubber material of AS3661.1, for which I have extensive experience and reference test data and some of which were used in particular for the acquisition of the date of Table 1. I also made measurements using Ms Sprowles’ shoes. In these measurements the test weight was concentrated separately on sole and heel so as to distinguish the properties of these two components. Measurements were made with freshly cleaned 50 mm square sliders under a load of 3.6 kg, and at a speed of 100 mm/sec for dynamic coefficients. I am satisfied that when using the 4S rubber sole material this method gives results which agree with those of the Australian Standard method, usually to within about 10%. However, I prefer the ASTM method for accident investigations because of its versatility in allowing the use of various sole materials and actual footwear, its applicability in confined situations, on sloping surfaces, or in the presence of contamination, and the possibility it provides in some cases to investigate the effects of variations in sliding speed and vertical load. Results are given in Table 3 and are discussed below (section 4.4.4)”

Table 3 referred to in this part of the report was as follows (Blue AB 117): “TABLE 3 Friction coefficients – Concrete fire stairs Unit A, 24 College Street, Gladesville Sliding S D Surface ====== Old leather .28 .25 Rubber .72 .61 4S rubber .67 .57 Urethane synthetic .50 .33 PVC .48 .44 Steel .17 .14 New leather .22 .17 Sprowle shoe sole .45 .34 Sprowle shoe heel .56 .53”

Paragraph 4.4.2 of the report makes it clear that the testing method adopted by Professor Morton differed – but, in the absence of AS 3661.1:1993 and the ATSM method, in what respects cannot be ascertained – from that provided for in AS 3661.1:1993, and, further, would seem to indicate that the results produced by each test are likely to differ by up to 10%, the test producing the higher result not being revealed.

In his report, Professor Morton also wrote (Blue AB 111): “ 4.4.3 Slipperiness of Ms Sprowles’ shoes I understand that Ms. Sprowles was wearing shoes as shown in Figures 8 and 9, which are photographs of the shoe I retained for measurement purposes. The shoes are marked as ‘made by Grosby’ and are shown as having synthetic uppers, linings and soles. Whilst it is unlikely that the accident would be considered to have been caused by the unsuitability or dangerous nature of Ms. Sprowles’ footwear, I considered it desirable to establish that the shoes themselves are not excessively slippery. I made measurements of the frictional grip of the sole and heel of the shoe against a number of typical walking surfaces. Results of the measurements are given in Table 3 and are discussed below (section 4.4.4).”

The reference, in paragraph 4.4.3 of the report to “Table 3” appears to me to have been intended as a reference to “Table 4”, which was as follows (Blue AB 177): “ TABLE 4 Friction coefficients – Ms. Sprowles’ sho es Floor Sole Heel Surface S D S D ===== ===== ===== Unpolished vinyl tiles .46 .42 .58 .54 Smooth glazed ceramic tiles .44 .39 .49 .47 Embossed glazed ceramic tiles .44 .37 .51 .47 Polished wood .41 .34 .48 .44 Smooth concrete .48 .35 .58 .50 Rough concrete .58 .54 .71 .68 ‘Non-slip’ ceramic tiles .55 .51 .69 .68 Loop-pile woollen carpet .61 .58 .80 .75”

The differing friction coefficients of the sole and heel of the Respondent’s shoes are – since they were made of the same compound (Black AB 121) – odd, a fact which was, in my view, not adequately explained by Professor Morton in the course of his cross-examination and re-examination (Black AB 121-123).

Professor Morton’s “discussion” of the results of his testing was as follows: “4.4.4 Slipperiness of the surfaces and safety From the results of Table 3 and judged on the basis of the criteria set out in Section 3 it is clear that for only footwear materials having a fairly high level of inherent grip are the treads sufficiently slip-resistant for safe use, even when dry and free of contamination. Although the treads have adequate grip for a rubber sole such as that specified for the requirements of AS3661.1, for other common synthetic sole materials such as those used in Ms Sprowles’ shoes the treads are sufficiently slippery to be dangerous and for soles of modest grip such as ordinary part-worn leather they are very dangerous. For inherently slippery materials such as hard smooth new leather the steps would be very dangerously slippery indeed.”

That “discussion” invites the following comments: a. notwithstanding that the passing of some 9½ years between the date of the incident of which the Respondent complained and the date of Professor Morton’s inspection, the surface of the stairs in question met – by a significant margin – the standard for surface friction laid down AS 3661.1:1993 and, seemingly, by BS 5395; b. that being so, the surface of the stairs was then to be regarded – but not by Professor Morton – as slip resistant; c. Professor Morton’s view would appear to be that meeting the standard laid down in AS 3661.1:1993 is not an adequate test of whether or not the surface of a floor is slip resistant and that the only way to determine whether or not a surface is, or is not, to be regarded as safe is by having regard to the coefficient of friction of the surface of the floor and the coefficient of friction of the type of sole actually, or likely to be, worn by those walking on the surface; d. if this is a correct assessment of Professor Morton’s view then it is quite impossible to reconcile that view with the existence of an Australian Standard, and Professor Morton, in my opinion, has provided no defensible reason for his view being preferred to that standard.

My view as to the value which might properly be attributed to Professor Morton’s report leads me to conclude that the Respondent, at trial, failed to make out an essential element – namely, that the stairs were slippery, and, thus, that the Appellant failed to take reasonable steps to secure her safety – in the case that she sought to make at trial, it following that the proceedings should have been dismissed.

I agree with the orders proposed by Heydon JA.

HEYDON JA: This is an appeal from orders of James J made on 27 April 2000. He entered a verdict for the plaintiff (respondent) in the sum of $1,153,886 and ordered the defendant (appellant) to pay the plaintiff’s costs. He did so after a six day trial, following which reasons for judgment were delivered on 22 December 1999, 14 April 2000 and 27 April 2000.

The Notice of Appeal contains two groups of challenges to the conclusion that the defendant was liable to the plaintiff, and several challenges to the quantum of damages. Grounds 1-3 on liability: was the defendant negligent? The facts

On 30 June 1986 the plaintiff fell at her place of employment on stairs leading from a car park on the roof of the building to the offices below where she worked. Associate Professor Morton, a physicist who specialised in the investigation of slipping accidents, was called as a witness in her case. After conducting various tests on the shoe which she said she was wearing on 30 June 1986, he reached the following conclusions about the stairs. “6.3 The tread surfaces are very smooth and are not provided with a non-slip finish throughout as is required by Ordinance 70. Neither are they fitted with non-skid strips near the edge of the nosings as required by Ordinance 70 as an alternative provision. 6.4 In the clean, dry condition the treads are adequately slip-resistant for safety only for footwear of inherently high-grip materials. 6.5 For other common footwear, including the shoes worn by Ms Sprowles the treads are sufficiently slippery to be dangerous even when clean and dry and would be very dangerous when wet, or if contaminated by loose powdery materials. The latter could well have been the situation at the subject time, due to the cracked condition of the stairway structures. 6.6 The dangerous condition of the treads could have been avoided easily and at low cost by the use of a wood-float or cross-brushed finish to the concrete treads, or the application of abrasive non-skid strips to the tread noses. The use of both provisions would have been preferable and in my experience would have been the usual practice in the industry at the time. 6.7 The accident to Ms Sprowles was caused by the dangerously slippery condition of the stairs provided for her use, in footwear such as she would reasonably have been expected to wear in the circumstances. 6.8 Ms Sprowles’ accident and consequent injuries resulted from a lack of proper care for her welfare on the part of those persons responsible for the provision of the stairs she used for access to her place of work.”

The trial judge made the following findings: “Counsel for the defendant did not dispute that on 30 June 1986 the plaintiff had fallen on the stairs leading from the car park on the roof of the building at Gladesville. Mr Firth said in his evidence that the plaintiff had told him some time in 1986 that she had had a fall on the stairs. It was also not disputed by counsel for the defendant that the defendant owed a duty to the plaintiff to take reasonable care to provide a safe means of access from the car park to the office where the plaintiff worked. Nor was it disputed that, if the plaintiff could establish that the stairs were slippery and that she had fallen because of the slipperiness of the stairs, she was entitled to a verdict. It was conceded that, if the stairs were slippery, there was a reasonably foreseeable risk of injury to the defendant’s employees including the plaintiff and there were reasonably practical steps the defendant could have taken which would have obviated the risk, which the defendant had not taken. I am prepared to accept the plaintiff’s evidence that the shoe which she produced to Professor Morton and which Professor Morton tested and which was later admitted as an exhibit, was one of the shoes she had been wearing at the time of the accident. I am also prepared to accept the plaintiff’s evidence that she had not worn those shoes much after the accident. If these matters are accepted, then I consider that Professor Morton’s conclusions should be accepted. Professor Morton was not really shaken in cross-examination (except at one stage when he fleetingly seemed to suggest that a coefficient of friction could depend on the pressure exerted on a surface) and there was no competing expert for the defendant. Professor Morton concluded that the surfaces of the treads of the stairs were very smooth, were not provided with a non-slip finish throughout or with non-skid strips near the edge of the nosings and for common footwear, including shoes of the type worn by the plaintiff, were sufficiently slippery to be dangerous, even when the stairs were clean and dry. I have reached the conclusion that the stairs were slippery, without resort to the evidence about there having been loose grit on the stairs, which, in Professor Morton’s opinion, would, had it been present, have increased the slipperiness of the stairs. I would not accept the evidence of either the plaintiff or Ms Blanch that they observed loose grit on the stairs. However, it does seem to me that, more probably than not, there would have been, by reason of the nature of the walls of the stairway, some grit on the stairs, which would have increased their slipperiness, even though the degree by which the slipperiness was increased cannot be quantified. The remaining question on liability is whether the plaintiff slipped because of the slipperiness of the tread of a step on the stairs or simply lost her footing. In her evidence the plaintiff merely said that her foot went out from underneath her. I find on the balance of probabilities that the plaintiff fell because her foot slipped owing to the slippery surface of the stairs. If a person is going down stairs and the stairs are slippery and the person loses her footing, then it is likely that the slipperiness of the stairs contributed to her losing her footing. I find a verdict for the plaintiff.”

Grounds 1-3 in the Notice of Appeal were: “1. His Honour erred in finding that Appellant was negligent. 2. His Honour [erred] in concluding the shoe tendered in evidence was a shoe worn by the respondent at the time of injury and that its condition at the time of trial was indicative of its condition at the time of the fall. 3. His Honour erred in accepting Professor Morton’s evidence.”

The defendant on the appeal advanced two groups of arguments against the conclusions of the trial judge. One group of arguments depended on attacking the trial judge’s substantial but not complete acceptance of the plaintiff’s credibility. The other group of arguments turned in large measure on attacking the trial judge’s reliance on Professor Morton. The defendant’s written submissions

The defendant’s written submissions on these topics took the following form. “8. The respondent was not an honest witness. She lied both in and out of Court, exaggerated in her evidence and attempted to mould the evidence so as to advance her case. His Honour so found (RB 68D-J). 9. In these circumstances, principle required His Honour ‘to carefully assess the rest of her evidence in order to determine its honesty and reliability. Some of her evidence may have been acceptable because it was confirmed by other independent or objective evidence. However, where the (respondent’s) evidence was not independently supported it clearly had to be assessed with great care to determine whether it could properly be accepted as proof of any matter that was in issue in the proceedings’ ( Malco Engineering Pty Ltd v Ferreira (1994) 10 NSWCCR 117 per Handley JA at 118D-E). 10. His Honour failed to approach the respondent’s evidence (other than that which the appellant had actually shown to be false) with the necessary caution or to subject it to appropriate analysis. As a result he accepted evidence which was not corroborated adequately or at all and which, on proper analysis, should have been rejected. This contributed to His Honour reaching erroneous conclusions as to all major issues in the trial. 11. His Honour concluded the stairs were slippery and that because of this the respondent had slipped and fallen (RB 72K-73T). 12. As a number of liability aspects were conceded by the appellant (RB 71S-72J) these findings enabled His Honour to find a verdict for the respondent which he did (RB 73U). 13. The appellant submits His Honour erred in finding that the stairs were slippery, that because of this the respondent slipped and fell and that the appellant was negligent. There was no evidence to sustain such findings as: (i) the Australian Standard provides that for a floor to be considered slip resistant a minimum value of 0.4 for the dynamic friction when tested against a certain standard simulated shoe sole (4S) hard rubber material must be obtained (Professor Morton, Blue Book 106R-T). This test was met (Blue Book 117H). (ii) It is generally accepted that above a coefficient friction of 0.4 a floor is safe (Black Book 120W-121C). The red shoes which the respondent said she was wearing at the time were not shown to have had a coefficient of friction of less than 0.4 at the time of the fall as: (a) the coefficient of friction of the shoe when measured by Professor Morton was above 0.4 save for one measurement of the dynamic friction of the sole (Blue Book 117P-Q); (b) Professor Morton’s measurements were made in December, 1995, some 9½ years after the event, by which time the surface of the stairs had suffered further wear (Blue Book 110M-O); (c) the shoes at the time of the fall would have been less worn than when tested and would have had more tread on them (Black Book 41H-J); (d) Professor Morton conceded that the coefficient of friction may have been affected by the shoe being worn after the accident, and that it may have been at the time of the occurrence that the coefficient of friction of the shoe was well within the parameters of safe walking (Black Book 121V-X). (iii) The evidence of the respondent was that she had been using the stairs every day for the period of her employment (Black Book 7J) without any problems (Black Book 41K-L). Mr Firth said that he wore leather-soled shoes and never had trouble negotiating the stairs and did not find them slippery (Black Book 162J-M). The evidence of Ms Blanch as to the state of the stairs was expressly rejected by his Honour (RB 71F-K). (iv) The respondent’s evidence that the shoe tested by Professor Morton was one that she had been wearing at the time of the accident and that she had not worn the shoes much after the accident (RB 72K-Q) should not have been accepted because - (a) the respondent in a statement dated 26 February, 1992 had said ‘she had disposed of the shoes since the accident’ (Blue Book 13P-R). When cross-examined her explanation was unconvincing (40Q-41D) and uncorroborated; (b) the respondent’s evidence as to the wearing of the shoes after the fall (8T-X, 40L-O) was inconsistent with the appearance of the shoe produced by Professor Morton (photograph Blue B 122) and her own comments as to the loss of tread (Black Book 41J); (c) the unsatisfactory and opportunistic nature of the respondent’s evidence (see paragraphs 8, 9 and 10 above). This was further illustrated in respect of the issue of the alleged grit on the stairs (an issue which ultimately was not relied upon by respondent’s counsel (RB 19B)). The respondent had not asserted her fall was the result of grit on the stairs prior to the hearing (Blue Book 107S-T). She did, however, accompany Professor Morton on his inspection of the premises and became aware that in the Professor’s opinion grit on the stairs could cause them to be slippery. When she came to give evidence she sought to take advantage of this (Black Book 9B-G, 41N-43H); (d) His Honour’s reasons for believing the respondent on this issue are unsatisfactory (RB 72K-P).”

The particular significance of the attack on the trial judge’s conclusions on credibility was that if the attack as framed were made good, considerable doubt would be cast on the plaintiff’s evidence that the shoe tested by Professor Morton was the one she was wearing at the time of the accident and also on her evidence that she had not worn the shoe much after the accident. If that were cast in doubt, the whole of Professor Morton’s testing, and the conclusions based on it, would cease to have validity. That in turn would make the plaintiff’s case on liability, which depended heavily on Professor Morton, extremely fragile. On the other hand, if the credibility findings and the testing stood, the plaintiff’s position would be improved, though the defendant did have numerous specific criticisms of Professor Morton’s conclusions even if the plaintiff’s credibility were accepted. The plaintiff’s credibility in general

Accordingly it is convenient first to examine the defendant’s arguments on credibility.

The trial judge dealt with the plaintiff’s credibility in considerable detail in the following way. “The extent to which the plaintiff’s evidence should be accepted is obviously crucial to a determination of this case. There was no witness, other than the plaintiff, to the alleged fall on 30 June 1986. Professor Morton’s conclusions were based on information supplied by the plaintiff that the shoes she produced to him were the shoes she had been wearing at the time of the accident and that she had not worn the shoes much after the accident. There is little or no orthopaedic evidence to support the plaintiff’s complaints of the symptoms and disabilities she says she has experienced. There is no evidence from Louise Adam, who was the first person to treat the plaintiff after the alleged accident, except a letter saying that Ms Adam’s notes about the plaintiff have been lost. The only medical evidence adduced on behalf of the plaintiff is the evidence of Dr Wilson, who first saw the plaintiff in January 1994, more than seven years after the accident. Dr Wilson accepted that the views he had formed depended on his accepting the plaintiff as a witness of truth about her symptoms. If the plaintiff is in fact able to do things which she claimed to Dr Wilson she could not do, then Dr Wilson would have to doubt the level of symptoms claimed by the plaintiff and, ultimately, even his diagnosis of fibromyalgia. There are other reasons as well why the plaintiff’s evidence is important. A strong attack was mounted by counsel for the defendant on the credibility of the plaintiff. Grounds for attacking the plaintiff’s credibility include the following. The plaintiff admitted that she had lied in part of her evidence. She initially denied that there had been any intentional acts of violence by Mr Dormer during their relationship. The breaking of her nose by Mr Dormer had been an accident. Later in the plaintiff’s evidence in chief she admitted that there had been incidents of violence, both before and after the accident, but ‘only a couple’. In cross-examination the plaintiff admitted that Mr Dormer had struck her ten to twelve times during the relationship. The plaintiff admitted that she had told lies out of court, for example, in complaining in 1984 to a counsellor at the Pre-Term Foundation that she had abdominal pain. The plaintiff gave some evidence which was inconsistent with previous out of court statements she had made. For example, she said in her evidence that her pregnancy had been terminated in 1990 because she was having problems with her breathing, whereas she had told a counsellor in 1990 that she felt she could not cope emotionally and financially with raising a child on her own, after her relationship with her partner had ended. The plaintiff had not mentioned to the counsellor any problems with her breathing. Furthermore, the plaintiff had said in her affidavit of 20 December 1995 that her problems with her breathing had started in August 1993. The plaintiff said in her evidence that there was grit on the stairs at the time of the accident, whereas she had informed Professor Morton at the time of their inspection on 11 December 1995 that, so far as she was aware, there was ‘no contamination or other adventitious material on the surface of the stairs’. She said in her evidence that she was getting worse in 1991 and 1992, which was contrary to what she had said in her affidavit of 20 December 1995 and what she had told Dr Wilson. It was submitted by counsel for the defendant that the plaintiff had exaggerated in her evidence. A notable example was that the plaintiff had exaggerated the difficulty she claimed she had in raising her right arm. In one of the videos the plaintiff was shown as extending her right arm vertically above and behind her head and maintaining that position for many seconds, without any apparent difficulty or any apparent discomfort. Dr Shand said in his last report that some of the results he obtained on his physical examination of the plaintiff contrasted significantly with her ability, when not actually being tested but while still being observed by Dr Shand, to move without restriction or signs of discomfort. It was also submitted that the plaintiff had attempted to mould parts of the evidence in such a way as to advance her case. An example was her evidence about there having been grit on the stairs at the time of the accident. It was submitted that the plaintiff had given this evidence, because she had been asked about the subject by Professor Morton at the time of the inspection and had come to appreciate that evidence from her that there was grit on the stairs would assist her case. Another example was her letter written to the Pre-Term Foundation in August 1996, seeking, six years after her pregnancy had been terminated, to supply an ex post facto reason for the termination which would assist her case. Counsel for the defendant pointed to the histories given by the plaintiff to some of her early carers, in which she had given a history of some incident or incidents other than, or as well as, the fall. The plaintiff had given Julie Chenery a history of having been the victim of domestic violence. The first item of history recorded by Mr Goodrich in his report was that the plaintiff had been pushed down on the top of her head. Louise Weavers recorded a history of a car accident in November 1988, which the plaintiff in her evidence denied had ever happened. It was submitted that the plaintiff’s attempts to explain why these histories had been recorded were unconvincing. Even Mr Firth said that the plaintiff had said to him that she had had a fall from a horse. It was submitted that the incident of the pushing down on the plaintiff’s head was particularly important. It was the first item of history recorded by Mr Goodrich in his report. Moreover, Mr Goodrich recorded that he had been told that it had happened two weeks before the ‘fall’. When the plaintiff initially gave evidence about this incident of Mr Dormer pushing down on her head, she said that it had happened about two weeks before the accident on 30 June 1986. Then she changed her evidence to saying that it had happened two weeks before her birthday on 14 October 1985. It was also submitted that the plaintiff had fixed ideas and had closed her mind about her medical condition and what had caused it. Everything, even catching glandular fever in 1989, was attributed by the plaintiff to fibromyalgia resulting from her fall. Any medical opinion or any medical advice which did not fit in with her fixed ideas about her condition and its cause was disregarded by her. It is clear that the plaintiff did, in one part of her evidence, lie and that she has lied out of court. I accept that some of her evidence was inconsistent with previous out of court statements she had made and I reject those parts of her evidence. I also accept that the plaintiff exaggerated in parts of her evidence, that she made some attempts to mould the evidence in such a way as to advance her case and that the plaintiff has fixed ideas about her condition and what caused it. I give weight to the submissions made concerning the histories given by the plaintiff. However, I note, as against the points made by counsel for the defendant, that Mr Goodrich did refer in his report to ‘a fall’ as being part of the history given to him; that Louise Weavers said quite explicitly in her report that, apart from the whiplash injury for which Ms Weavers was treating the plaintiff, the plaintiff said she had low back and left leg pain for which she was being treated by other practitioners, being an osteopath and a chiropractor; and that Anne Petrie said in her report ‘the history given was onset of symptoms occurred after falling at work on 30 June 1986’. I do not give any weight to Mr Firth’s rather vague evidence that the plaintiff had said that her condition ‘was something to do with a fall from a horse’. The only evidence of a fall from a horse is of a fall in about 1971. I accept generally that it is likely that the plaintiff was asked by those from whom she sought treatment whether she could remember any incident which could have contributed to her condition. I have concluded that the incident in which Mr Dormer pressed down on the plaintiff’s head did involve more physical force than the plaintiff conceded in her evidence. Despite these well founded criticisms of the plaintiff’s credibility, I have concluded that she was not generally malingering and I have also concluded that I should accept most of her evidence, even though rejecting some parts and discounting some other parts to some extent as being exaggerated. I have explicitly referred in this part of my judgment to most parts of the plaintiff’s evidence which I have decided I should reject. Objective matters which lend support to the general tenor of the plaintiff’s evidence include that she had worked virtually continuously from about 1971 up to June 1986; that she was clearly ambitious to succeed in her career; that prior to 30 June 1986 she had made few if any complaints and had sought very little medical or paramedical attention; that commencing from 10 July 1986 the plaintiff constantly over many years and at considerable expense to herself sought paramedical attention; that the plaintiff continued working from 1986 to 1992, although constantly seeking and receiving treatment; that the plaintiff made a formal claim for compensation in late 1991, before Mr Weekes commenced employment with Makita and hence before the sexual harassment started. The plaintiff’s evidence is corroborated in a number of respects by the evidence of her mother, Lois Dinuzzo, Georgina Morgan and Natalie Blanch. I generally accept the evidence of those witnesses, except that I do not accept that Ms Dinuzzo had any real recollection that the telephone call she received from the plaintiff was ‘towards the end of 1986’ and I do not accept Ms Blanch’s evidence about the state of the concrete stairs in the building at Gladesville. Her evidence that she had used the concrete stairs to go from one floor to another in the building seems to be inconsistent with the evidence of Mr Firth, whose recollection would be likely to be accurate, that there were internal stairs for persons moving from one floor to another within the building. Of these witnesses I was particularly impressed by Georgina Morgan, who, apart from her generally persuasive demeanour, had the advantage of having lived with the plaintiff and Mr Dormer from February 1986 to early June 1986, that is until just before the accident.”

Counsel for the defendant at numerous stages in his oral argument pointed to the aspects in respect of which the trial judge had noted that the plaintiff lacked credibility, and gave further illustrations.

Counsel for the defendant appeared to disavow any attempt to fit the present circumstances into any exception to the general immunity which the findings of trial judges based on credibility enjoy. This is understandable. It cannot be said that the trial judge failed to use or palpably misused the advantage he had of seeing and hearing the plaintiff, or that the trial judge relied on evidence which was inconsistent with facts incontrovertibly established by the evidence, or that the trial judge acted on evidence which was glaringly improbable, or that the trial judge fell into some error of principle, or that the trial judge mistook or misapprehended the facts, or if the effect of the overall evidence was such that it was not reasonably open to make the findings he did: Abalos v Australian Postal Commission (1990) 171 CLR 167; Devries v Australian National Railways Commission (1993) 177 CLR 472; Rosenberg v Percival (2001) 75 ALJR 734 at [37]-[42] and [92] per McHugh J and Gummow J. Nor can it be said that the case is one “where in a complex pattern of events incontrovertible evidence can only be fitted into the pattern if a different view of the credibility of a witness is taken by the court on appeal”: Agbaba v Witter (1977) 51 ALJR 503 at 508 per Jacobs J; approved in State Rail Authority of New South Wales v Earthline Constructions Pty Ltd (In Liq) (1999) 160 ALR 588 at [4] by Gaudron, Gummow and Hayne JJ. The reasons for judgment of the learned trial judge in all respects appear to be the product of the most painstaking analysis of the facts in an extremely unusual and difficult case. His comments are detailed, well-organised, careful and balanced. Counsel for the plaintiff submitted that the trial judge had provided “a model of judgment writing”, and that is true. He had excellent opportunities to observe the plaintiff over long periods she was in the witness box on different parts of three days. If it matters, the trial judge has immense experience in presiding over trials, including trials involving factual conflicts even more acute than the acute conflicts involved in this case and trials where much more was at stake than the large sums of money involved in this case.

Instead, counsel for the defendant contended that the trial judge had not complied with the passage set out above from Handley JA’s reasons for judgment in Malco Engineering Pty Ltd v Ferreria (1994) 10 NSWCCR 117 at 118. That contention is not made out. Handley JA did not say that where a party-witness has lied, the balance of the testimony can never be accepted without corroboration. All he said was that the balance of the testimony in that case called for careful assessment. What the trial judge here provided was careful assessment. Counsel for the defendant fell back onto the contention that while the trial judge could have accepted parts of the plaintiff’s evidence, he could not do so without “proper reason”. He said: “Just because they say something, you can’t just accept that when you know they’re a liar.” But though the trial judge gave no reason for accepting the evidence of the plaintiff about the fact that the shoe Professor Morton tested was the shoe she wore, and about how much she wore it after the accident, he was entitled to accept her evidence on the basis of the overall character of her testimony, part of which was to be disbelieved for particular reasons, part of which was to be believed because it was corroborated, and part of which was, though not corroborated, not affected by any particular reason not to accept it. Finally, counsel for the defendant said that even if the approach for which he was contending was not a universal rule, it was appropriate to employ it in particular cases, and this was one. The difficulty is that it has not been shown that the trial judge failed to assess and analyse the totality of the plaintiff’s evidence against the background of the other evidence in such a way as to cast doubt on his conclusions that substantial parts of her evidence could be accepted. It is common enough in litigation for witnesses with a truthful story to succumb to the temptation of gilding the lily or over-egging the pudding. The test for the trier of fact is to separate the truthful parts from the rest. While it may be that other triers of fact would have arrived at conclusions different from those of the trial judge in this case, the fact is that the conclusions that he arrived at were not implausible. The weaknesses of parts of the plaintiff’s evidence here, while troubling, were not so great as to call for a rejection of all the uncorroborated parts of it. The plaintiff’s credibility about her shoes

Counsel for the defendant did not limit himself to the generalised attack on the trial judge’s credibility findings just discussed. As indicated above, he offered particular arguments critical of the findings about the shoes. One category of these arguments turned on supposed inconsistencies within the plaintiff’s evidence, and between her evidence and a photograph of one of the shoes. The inconsistencies in the plaintiff’s evidence in this respect, if they exist at all, are only slight. The photograph appearing in the appeal book does not point strongly towards any inconsistency between its condition and her evidence, if only because the detail of the surfaces of the shoe does not show up clearly. The other particular argument advanced turned on a statement supplied to an insurance investigator by the plaintiff on 26 February 1992. In it she said: “At the time I was wearing a pair of flat red shoes which I have since disposed of.” On 11 December 1995 the plaintiff gave Professor Morton a pair of shoes which she told him she was wearing on 30 June 1986, and he tested them. In chief the plaintiff gave the following evidence: “Q. Do you recall now how long you had owned those shoes prior to the accident? A. Not very long, probably two months. Q. Had you worn them often during the time you had owned them? A. Probably once a week. Q. Subsequent to the accident did you continue to wear the shoes? A. For a short period of time and then I stopped. Q. Do you recall how long that was now after the accident that you continued to wear [the] shoes? A. I would be guessing. Q. With what frequency, daily, weekly? A. I would never wear them more than once a week.”

In cross-examination the plaintiff gave the following evidence: “Q. You had a pair of shoes which you produced to the court yesterday which you had for some two months and only wore once a week? A. I think I had them longer than two months. I always wore them two or three months after the fall. Q. I think you said in your evidence yesterday that you had them for two months and that you wore them for a few months after the accident as well? A. Could be right, it was a long time ago. Q. They were relatively new shoes I take it? A. Yes. Q. And you have kept them all this time? A. I put them in [a] box to throw away and thought I had thrown them away but I found them by accident when I was cleaning out my shed, I found a box full of old shoes and I went through the box and thought: Oh there is my red shoes, I thought I had thrown them away. Q. When did you find them? A. I was living at Kellyville at the time so it would have been after October 1990. When it was exactly I don’t know. Q. Some time in the 90’s. Is that right? A. Yes, this was in the 90’s. Q. Was that before or after you had commenced action against your employer? A. This action? Q. Mmm? A. Before. Q. Why did you keep them? Were you thinking about bringing action at that stage? A. No, I went through the box and I threw out some of them and those ones I thought: They are unlucky but maybe I will wear them in the future. Q. Did you have other red shoes? A. Yes, I had a pair of red shoes in the 70’s, the old clog style shoes. Q. There is no doubt in your mind that they were the shoes you were wearing on that day? A. Yes.” This Court was not taken to any passage in which the plaintiff was confronted with the statement she gave to the insurance investigator on 26 February 1992 and asked to reconcile it with Professor Morton’s evidence and her own cross-examination. The failure to challenge her explanation in that way would have made it easier for the trial judge to accept that explanation. The written submissions advanced on behalf of the defendant at the trial do not appear to have challenged the explanation. Perhaps for that reason, the trial judge does not appear to have dealt specifically with the conflict between the 26 February 1992 statement and the plaintiff’s sworn evidence. The trial judge’s conclusions involve an implied acceptance of her explanation in cross-examination. That acceptance is not something which can be upset on appeal unless some exception to the Abalos doctrine applies. None has been pointed to.

It follows that the defendant’s contention that the plaintiff’s evidence about the identity of the shoe and the degree of its use after the accident should not have been accepted fails. That in turn means that Professor Morton’s reasoning can stand on its merits, because the assumptions of primary fact underlying it were sufficiently established. One explicit assumption was the identity of the shoes, and that was totally established. Professor Morton said in cross-examination that he assumed that the relevant shoe had not been significantly worn after the accident. That corresponds substantially with the fact, namely that it had not been worn much. Complete precision in proof of facts intended to support the assumptions of an expert is not called for; it is enough if the case proved is sufficiently like the case assumed to render the expert’s opinion valuable: Paric v John Holland (Constructions) Pty Ltd (1985) 59 ALJR 844. The defendant’s attack on Professor Morton

Counsel for the defendant, however, contended that Professor Morton’s reasoning, even accepting that the assumptions underlying it had been established, was invalid.

In order to understand Professor Morton’s reasoning and the defendant’s criticism of it, it is necessary to appreciate that at its heart were certain tests he conducted. They were conducted in order to assess compliance of the stairs with certain tests for friction suggested by standards described by Professor Morton as follows (para 3.6): “Until recently there have been no Australian or other national standards for surface friction of floors or footwear. An Australian Standard (AS 3661.1:1993) was issued in October 1993. This document sets a minimum value of 0.4 for the dynamic friction, dry or wet, when tested against a certain standard simulated shoe sole (4S) hard rubber material for a floor to be considered as slip-resistant. It should be noted however that a floor satisfying this requirement is not necessarily safe, and particularly not for use by other types of footwear or under other conditions. A second part of the Standard (AS 3661.2:1994) dealing with methods of reduction of slipping hazards has been issued (February 1994). British Standard BS 5395 for steps and stairs also indicates that a dynamic coefficient below 0.4 is unsatisfactory. Whilst there are no universally agreed standards for floor friction it is usually accepted that dynamic friction coefficients below 0.4 are unsafe whereas above 0.5 they are safe.”

Professor Morton conducted two types of tests.

The first type consisted of tests conducted on the stairs 9½ years after the accident using various shoe materials. The purpose of these tests was to measure the slipperiness of the stairs. One of the shoe materials tested on the stairs was the 4S hard rubber material referred to in the passage quoted above. Two others were the plaintiff’s shoe sole and the plaintiff’s shoe heel. That test revealed that for 4S rubber the static friction coefficient was 0.67 and the dynamic friction coefficient was 0.57. Those figures are well above the minimum value of 0.4 set out in AS 3661.1:1993 and the equivalent British standard. That test also revealed that for the plaintiff’s shoe sole the static friction equivalent was 0.45 and the dynamic friction coefficient was 0.34. For the plaintiff’s shoe heel the respective figures were 0.56 and 0.53.

The second type of test conducted by Professor Morton had the purpose of testing the slipperiness, not of the stairs, but of the plaintiff’s shoe (see para 1). Professor Morton took the plaintiff’s shoe sole and shoe heel and tested them, not against the actual stairs, but against a variety of surfaces of which the closest to the stairs was a surface described as “Smooth concrete”. For the sole the static friction coefficient was 0.48 and the dynamic friction coefficient was 0.35. For the heel the corresponding figures were 0.58 and 0.50. The significance of the figures for “Smooth concrete” stems from the following account by Professor Morton of the materials used on the stairs (para 4.3.2): “The stairs are constructed of reinforced cast concrete. The tread surfaces appear to have received what is generally known as a wet steel trowel finish. This involves trowelling the wet partly-set concrete with a smooth steel tool, often with the addition of further dry cement to achieve a hard, dense and very smooth surface. The resultant moderately high shine of the concrete treads may be seen in Figure 7, a photograph taken in ambient light.” He also spoke of “this highly and deliberately smoothed concrete surface” (para 4.3.2) and of “the very smooth concrete stair treads” (para 5.1).

In the first group of tests, the purpose of which was to measure the slipperiness of the stairs, the measurement of the dynamic friction coefficient of 4S rubber was well above both the 0.4 level and the 0.5 level. Thus the first group of tests placed 4S rubber well above both the 0.4 level and the 0.5 level. The first group of tests on the plaintiff’s shoe, however, revealed that her sole had a dynamic friction coefficient below 0.4. Professor Morton’s conclusion about this group of tests was put thus (para 4.4.4): “From the results of Table 3 and judged on the basis of the criteria set out in Section 3 it is clear that for only footwear materials having a fairly high level of inherent grip are the treads sufficiently slip-resistant for safe use, even when dry and free of contamination. Although the treads have adequate grip for a rubber sole such as that specific for the requirements of AS3661.1, for other common synthetic sole materials such as those used in Ms Sprowles’ shoes the treads are sufficiently slippery to be dangerous and for soles of modest grip such as ordinary part-worn leather they are very dangerous. For inherently slippery materials such as hard smooth new leather the steps would be very dangerously slippery indeed.”

The tests in the second group were undertaken to test, not the slipperiness of the stairs, but the slipperiness of the plaintiff’s shoes (paras 1 and 4.4.3). At para 4.4.3 Professor Morton said: “Whilst it is unlikely that the accident would be considered to have been caused by the unsuitability or dangerous nature of Ms Sprowles’ footwear, I considered it desirable to establish that the shoes themselves are not excessively slippery. I made measurements of the frictional grip of the sole and heel of the shoe against a number of typical walking surfaces. Results of the measurements are given in Table 3 and are discussed below (section 4.4.4).” These references appear to be erroneous: in fact the results of the measurements were given in Table 4 and discussed in para 5.1. Professor Morton’s only reference to the results of the second set of tests, set out in Table 4, is (para 5.1): “Although not of the highest grip materials there is no reason to consider that the soles of Ms Sprowles’ shoes were excessively or unusually slippery (see Table 4). They are in my experience rather better than average in the level of grip afforded by ladies shoes.” Professor Morton offered the following “discussion” of “accident causation”: “It is evident that the accident to Ms Sprowles was caused by the inadequate frictional grip afforded by the very smooth concrete stair treads for her footwear. … Whilst the interface between Ms Sprowles’ shoes and the step treads should not be classed as very slippery, the level of grip afforded is below that needed for a reliable margin of safety. It might be possible for a user to walk on these steps many times without undue incident until one day, due to random variations in gait pattern, exerting slightly more lateral force on the floor contact than usual and consequently slipping and falling.” He then discussed the possible impact of any loose grit on the stairs in a manner which need not be quoted, since the trial judge concluded that the stairs were slippery without reference to that factor, and said that while there probably was grit on the stairs, the degree by which it increased their slipperiness could not be quantified.

Professor Morton then offered the following “discussion” of “foreseeability, avoidability and liability” (para 5.2): “The generally low slip-resistance of smooth surfaces, especially compared to the higher grip of roughened surfaces of the same material is a matter of common experience which may be readily appreciated without the need for any special experience or extensive study of the friction of surfaces. It thus would or should have been evident to those persons responsible for the provision of the subject stairs that they would be likely to be slippery and dangerous. It should also have been obvious to them that the stairs were likely to be particularly dangerous in the presence of any powdery or other loose particulate material such as sand or debris from building cracks. Although not of direct relevance to Ms Sprowles’ accident, to have provided a smooth surface for fire stairs, in a location where, foreseeably, they are likely to become wet in rainy conditions is particularly imprudent. The extreme and dangerous slipperiness of wet smooth non-porous surfaces is well-known. The evident lack of care for the welfare of users of the stairs exhibited by the choice of smooth surface as provided is magnified when it is considered that the use of a concrete wood-float finish would have greatly reduced the risks to which users are exposed. It is ironic that the costs of using such a finish probably would have been less than that involved in the skilled trowelling process used to produce the present smooth shiny concrete surface. Cross-brushing, which would have been even better, also is a simple and very low-cost process. Some small extra cost would have been involved in fitting non-skid strips, but abrasive strips simply surface-applied by adhesive are widely and readily available. Even given the slippery nature of the smooth overall tread finish, reasonable safety could have been achieved by the application of such strips even after the stairs were built. Although not providing full slip-resistance, particularly on extended areas such as landings these are better than nothing and would formally satisfy the requirements of Ordinance 70. Had such strips been fitted, which in my view is essential to prevent the present treads being very dangerous when wet, or sandy, they would also probably have prevented the accident which occurred to Ms Sprowles. Hence it appears that in this case the accident to Ms Sprowles was caused by the dangerously slippery condition of the stairs provided for her use, in footwear such as she would reasonably have been expected to wear in the circumstances. The danger which caused the accident would or should have been foreseen and could have been prevented by simple low-cost and readily available means. The question of liability of course must ultimately be for the Court to decide, but it appears that Ms Sprowles’ accident and consequent injuries resulted from a lack of proper care for her welfare on the part of those persons responsible for the provision of the stairs she used for access to her place of work." Professor Morton then set out the conclusions quoted in [25] above.

The principal part of Professor Morton’s cross-examination which is relevant is as follows (Black 120R-122J): “Q. And ordinarily dry this surface was slip resistant? A. No, I would not agree with that. Q. When do you say the coefficient of friction occurs that is dangerous, there is a defined point, is there not? A. The defining point depends on many things including the footwear. Someone wearing high grip gum boots or something of that sort would be reasonably safe on these stairs. In dry conditions wearing shoes such as the ones that Ms Sprowles showed me that she was wearing would not be reasonably safe. Someone wearing other shoes would find those stairs dangerous. Q. In the scenes [sic: scilicet ‘science’] of slippery surfaces there is a recognised coefficient of friction below which it is clearly dangerous? A. 0.4 is commonly adopted, below which it is generally accepted if there is a coefficient of friction there is a significant danger that it is not safe, but above that it is safe. Q. And that is the touchstone commonly used in these cases? A. Yes. Q. That is the upper level, the lower level is 0.3? A. There are one or two people who suggest that 0.4 is generally accepted and 0.5 is when you can expect you are going to have a reasonably safe surface. Q. Does it make a difference whether the tip or sole of her foot touched stairs? A. It does make a difference. In the exceptional circumstances of someone wearing high heels the toe goes down followed by the heel. Q. But it may be that she did that? A. No, I do not accept that. The toe goes down first, unless one is wearing high heels and then the heel cannot be placed on the step first. Q. The heel and the sole of this shoe are the same material? A. I think not, if it is the shoe that I tested. Q. (Shown Exhibit B). Are you seeing there is a difference between the sole and heel of the shoe? A. The two materials are the same, but the coefficient of frictions are somewhat different. The sole is somewhat smoother than the sole [sic; scilicet ‘heel’]. Q. Would the smoothness of the sole make some difference? A. I would not expect a large difference. I will refer back to my notes on this one. I accept that the difference is larger than I expected on visual inspection, but, on the other hand, from experiences one can be deceived from looking at the surface and depicting what it is likely to be. Q. The shoe, I would like you to assume, had been worn after the accident. We do not know how long but for some period of time. That may have affected the coefficient of friction, would it not? A. Perhaps. Q. Do you agree they appear to be the same compound material? A. Yes. Q. Although the texture is different? A. Yes. Q. And it may have been at the time of this occurrence the coefficient of friction was well within the parameters of safe walking? A. Speculation, but yes, it is possible. Q. It is speculation to assume from the shoe that you see now, when you tested it, now some time after the event, that the coefficient of friction that the shoe was displaying was the same at the time of the accident? A. The tests were done and my conclusions were reached on the basis of the assumption that the shoe had not been significantly worn since the accident. Q. It is significantly accurate, is it not? A. That is the information I received. Q. No doubt you have seen many occasions when people walking downstairs miss their footing, no problems with the stairs they just lose their footing? A. Yes. Q. And that may have happened here if the coefficient of friction was different at the time of the accident to the time when you tested the shoe? A. That is always possible, yes.”

The defendant made various points about Professor Morton. They do not, taken separately or together, appear to be decisive reasons for rejecting his conclusions.

The first point made by the defendant was that in the first group of tests, the static and dynamic coefficients of friction of 4S rubber were both “well and truly over the 0.4 which was the baseline for a floor to be considered as slip resistant”. Reference was made to Professor Morton’s evidence in chief and in cross-examination on that point. The problem is that Professor Morton said that even if the dynamic coefficient of friction for 4S rubber exceeded 0.4, “a floor satisfying this requirement is not necessarily safe, and particularly not for use by other types of footwear or under other conditions” (para 3.6).

The second point made by the defendant was that in the first group of tests, the measurements for the plaintiff’s shoe had only one below 0.4, and in the second group of tests the test of the plaintiff’s shoe on smooth concrete produced only one figure below 0.4. However, if one accepts Professor Morton, the former fact alone made the step unsafe, and perhaps the latter fact alone as well.

The third point made by the defendant was that Professor Morton’s tests were carried out 9½ years after the accident, and in that period the surface of the stairs had suffered wear and was more slippery than at the time of the accident. Professor Morton said that the tread edges had become polished by wear, and the degree of polish had increased since 1986. The defendant said that by parity of reasoning, if the tread edges had become polished so had the entire surface. However, what Professor Morton said was (para 4.4.1): “I made spot tests of frictional properties in various positions on the stair treads. The tread edges have become polished by wear and although difficult to measure appeared to be more slippery than the flats of the treads. They thus might be considered to be unlikely to prevent a slip of a foot placed too close to the tread edge. However, this polish is likely to have increased in the years since the accident, and is in any event relevant only to a foot which has been significantly misplaced. In my view the degree of polish of the tread edges should not be regarded as a significant circumstance of the accident. Otherwise the preliminary tests indicated that there were no local variations in properties sufficient to be of practical importance in regard to safety. I chose to make measurements at the front of the third tread down as being the position at which Ms Sprowles slipped but it is considered that neither the particular location chosen for detailed measurements, nor of the alleged accident itself are of significance for the conclusions of this report in regard to slipperiness of the treads.” This appears to indicate that the tread flats were less slippery than the tread edges. Though it is a natural suspicion that the tread flats apart from the tread edges became more slippery over 9½ years, Professor Morton was not cross-examined as to whether the “parity of reasoning” relied on was valid reasoning.

The fourth contention of the defendant was that the shoes at the time of the accident would have been less worn than when they were tested. But Professor Morton assumed that this was so only to a small degree, the evidence of the plaintiff which the trial judge accepted matched that assumption, and it is not possible for this Court to substitute a finding that the shoes were more heavily worn.

Finally, the defendant submitted that if one allowed for the wear on the steps and the wear on the shoes in the 9½ years from the accident, a reading in 1986 would have been 0.4 or better, and that Professor Morton conceded this. However, in fact all that Professor Morton conceded was that that was a possibility. For this type of argument to succeed in a direct assault on Professor Morton’s reasoning it is necessary to demonstrate, or point to a concession, that it was a probability, not just a possibility. Another aspect of Professor Morton’s evidence

However, the defendant did point to powerful evidence given by witnesses other than Professor Morton which bears on the issue of liability. That evidence, taken with some other difficulties in Professor Morton’s evidence, indicates that the trial judge erred.

The defendant pointed out that the plaintiff had begun to work with the defendant on 16 January 1984, nearly 2½ years before the accident. She took the route from the car park down the stairs to her office every day. That evidence needs to be taken with other evidence to which the defendant did not point: her office was on the first floor; there were 14 steps from the rooftop doorway to a half landing, and yet further steps before the first floor was reached (Professor Morton para 4.2); though the defendant had premises on the ground floor as well, the plaintiff’s office was on the first floor. It follows that in the period of her employment the plaintiff could have walked down a substantial number of steps on as many as 600 days. Since Professor Morton’s strictures were directed not just against the step on which she fell, but all the steps (para 4.4.1), she had an extremely large number of opportunities to slip. Yet, as the defendant pointed out, she gave evidence that she had never had any problems in using the stairs. The defendant also pointed out that the plaintiff’s immediate superior, Mr Firth, who was called by the defendant, gave the following evidence (Black 162G-P): “Q. When you went to work how did you travel? A. I drove the car and parked at the roof car parking. Q. Did you use the stairs that led from the roof into the building on a regular basis? A. Yes, yes Q. What sort of shoes did you wear? A. They were leather soled, sometimes some had a rubber heel. Q. Did you ever have trouble negotiating those stairs? A. No. Q. Did you ever find them slippery? A. No. Q. Do you recall in 1986 whether or not there was any extraneous substances on the stairs regularly? A. No, not to my knowledge. I never saw it. Q. By that I mean builder’s dust or anything of that nature, do you recall seeing anything like that? A. No.” His office was on the first floor. Mr Firth was not cross-examined on that evidence. The defendant pointed out that Professor Morton indicated that leather was a more slippery material than the material of which the plaintiff’s shoes were composed (see para 4.4.4 and Table 3). Mr Firth’s failure to notice any slipperiness in the stairs is thus significant. To those submissions could be added the fact that Professor Morton said that from “my observations it is clear that the present occupants regularly use the fire stairs for access between the roof and the two interior floors of the building” (para 4.1). Yet there is no evidence that any other persons engaged in the defendant’s business had ever encountered relevant problems on the stairs either before or after the accident. The plaintiff continued to work there after 30 June 1986 until 7 December 1992, and would have good opportunities to hear of any problems in view of her own fall.

In these circumstances, were it not for Professor Morton’s report, a conclusion that the stairs were not slippery would have been inevitable.

However, Professor Morton said in effect that the accident-free history of the steps was immaterial (para 5.1): “Whilst the interface between Ms Sprowles’ shoes and the step treads should not be classed as very slippery, the level of grip afforded is below that needed for a reliable margin of safety. It might be possible for a user to walk on these steps many times without undue incident until one day, due to random variations in gait pattern, exerting slightly more lateral force on the floor contact than usual and consequently slipping and falling.”

It is accordingly necessary to examine Professor Morton’s report closely.

If Professor Morton’s report were to be useful, it was necessary for it to comply with a prime duty of experts in giving opinion evidence: to furnish the trier of fact with criteria enabling evaluation of the validity of the expert’s conclusions. In Davie v The Lord Provost, Magistrates and Councillors of the City of Edinburgh 1953 SC 34 at 39-40, Lord President Cooper, in a case concerning liability for damage to dwelling houses allegedly caused by blasting operations in the course of constructing a sewer, said: “The only difficulty experienced by the Lord Ordinary and developed before us arose from the scientific evidence regarding explosives and their effect. This evidence was given by Mr Teichman, one of the technical staff of the I.C.I., with whom a fellow employee, Mr Sheddan, was taken as concurring. Mr Sheddan was cross-examined on his qualifications with considerable effect, and the point was taken that Mr Teichman was truly uncorroborated. I do not consider that in the case of expert opinion evidence formal corroboration is required in the same way as it is required for proof of an essential fact, however desirable it may be in some cases to be able to rely upon two or more experts rather than upon one. The value of such evidence depends upon the authority, experience and qualifications of the expert and above all upon the extent to which his evidence carries conviction, and not upon the possibility of producing a second person to echo the sentiments of the first, usually by a formal concurrence. In this instance it would have made no difference to me if Mr Sheddan had not been adduced. The true question is whether the Lord Ordinary was entitled to discard Mr Teichman’s testimony and to base his judgment upon the other evidence in the case. Founding upon the fact that no counter evidence on the science of explosives and their effects was adduced for the pursuer, the defenders went so far as to maintain that we were bound to accept the conclusions of Mr Teichman. This view I must firmly reject as contrary to the principles in accordance with which expert opinion evidence is admitted. Expert witnesses, however skilled or eminent, can give no more than evidence. They cannot usurp the functions of the jury or Judge sitting as a jury, any more than a technical assessor can substitute his advice for the judgment of the Court … . Their duty is to furnish the Judge or jury with the necessary scientific criteria for testing the accuracy of their conclusions, so as to enable the Judge or jury to form their own independent judgment by the application of these criteria to the facts proved in evidence. The scientific opinion evidence, if intelligible, convincing and tested, becomes a factor (and often an important factor) for consideration along with the whole other evidence in the case, but the decision is for the Judge or jury. In particular the bare ipse dixit of a scientist, however eminent, upon the issue in controversy, will normally carry little weight, for it cannot be tested by cross-examination nor independently appraised, and the parties have invoked the decision of a judicial tribunal and not an oracular pronouncement by an expert.” Lord Carmont expressed “complete agreement” with those views. Lord Russell said at 42: “The opinion expressed by an expert witness in any branch of technical science depends for its effect on, inter alia , his qualifications, skill and experience in that science. If it appears to be based on a sufficiency of research directed accurately and relevantly to a particular issue and to be so supported as to convince a Court of its fundamental soundness and applicability to the particular issue, a Court is entitled, although not obliged, to accept it, even if unsupported by any corroborative expert opinion. Secondly the defenders argued that in the absence of any counter evidence of expert opinion in the science professed by Mr Teichman the Court is bound to take his opinion as conclusive, and as decisive of the issue. I am clearly of opinion that that argument must be rejected as being contrary to the principles by which the rules of evidence are regulated, and as constituting an unwarrantable encroachment on the judicial function of the Court. I respectfully agree with your Lordship’s observations on that topic … .” Lord Keith concurred with all the opinions expressed.

Davie’s case is not to be read as reflecting only a principle peculiar to Scottish law. Before it was decided, in R v Jenkins ; ex parte Morrison [1949] VLR 277 at 303, Fullagar J said that an expert witness must “explain the basis of theory or experience” upon which the conclusions stated are supposed to rest, for, as Sir Owen Dixon said in an extra-judicial address quoted by Fullagar J, “Courts cannot be expected to act upon opinions the basis of which is unexplained”.

Since the decision in Davie’s case, the approach of Lord President Cooper in particular has been adopted by the following: Gordon J Samuels, “Problems Relating to the Expert Witness in Personal Injury Cases” in (ed) Harold H Glass, Seminars on Evidence (Law Book Co Limited, 1970), p 141; Phipson on Evidence (15th ed, 2000) paras 37-01 and 37-50; Lysaght v Police [1965] NZLR 405 at 409; Re B (A Minor) (Care: Expert Witnesses) [1996] 1 FLR 667 at 670; O’Kelly Holdings Pty Ltd v Dalrymple Holdings Pty Ltd (1993) 45 FCR 145 at 155 per Spender J, quoted by Sweeney and O’Connor JJ ; Idoport Pty Ltd v National Australia Bank Ltd [2001] NSWSC 123 at [13]; R v Gilfoyle [2001] 2 Cr App R 57 at [25]. In the last case Rose LJ, the Vice President of the Court of Appeal (Criminal Division), Hallett J and Crane J had under consideration a psychologist who was an expert in the systematic analysis of human behaviour called to give an opinion that a deceased person whom the appellant had been convicted of murdering had in fact committed suicide. Rose LJ said that “the evidence tendered from him was not expert evidence of a kind properly to be placed before the court for a number of reasons.” One of those reasons was that “his reports identify no criteria by reference to which the court could test the quality of his opinions”. Though Rose LJ spoke in terms of admissibility, not weight, the point he made can apply equally to the weight of evidence, even evidence like that of Professor Morton, which was admitted without objection and was not contradicted by an expert called by the defendant.

Despite these authorities, it might be argued that the approach adopted in Davie’s case is erroneous. The competing view, which has had some currency in the profession, is that all an expert need do is establish that there is a relevant field of specialised knowledge; that he or she has expertise in a relevant aspect of it; and that he or she holds opinions relevant to the establishing of one or more of the facts in issue in the litigation. It has sometimes been said, for example, that all a valuer need do is establish valuation expertise, prove that that which is to be valued has been examined by the valuer, and give an opinion on what the value is. The opposing party would then have two choices. The first is to cross-examine in the dark, with the perils which usually face journeys into darkness, to establish the factual assumptions underlying the valuation, and the relationship between the valuer’s conclusion and the valuer’s expertise as applied to those assumptions. The second is not to cross-examine, and run the risk of the court attaching weight to the opinion, ill-substantiated though it may be on its face.

Whether or not the method of giving expert evidence just described has ever been widespread or has attracted the approval of trial courts is hard to say. Bramwell B in Sheen v Bumpstead (1862) 1 H & C 358 at 365; 158 ER 924 at 926-7, said: “The mistake, as I think it, seems to me the same as where, on the question what is the fair price of a piece of land, an inquiry is proposed as to the price at which a piece of neighbouring land similarly circumstanced sold, or where the question is, what is the fair price of wheat on such a day, and it is asked at what price. A. then sold such wheat to B. The proper question in each case to the expert is, what is the fair or market price. On cross-examination he may give, as his reason, because such a piece of land was sold at such a price, and because A. sold wheat at such a price to B., and any other reasons; but he cannot be asked those particular questions on the examination in chief.” In English Exporters (London) Ltd v Eldonwall Ltd [1973] Ch 415 at 423 Megarry J said: “this … was an obiter remark in a dissenting judgment … and for many years now such evidence has not been rejected in chief when the witness has been speaking from his own first-hand knowledge.” The correctness of Bramwell B’s view even at the time is questionable: see R v Murphy (1837) 8 C & P 297 at 306-307; 173 ER 502 at 507. According to Phipson on Evidence (15th ed, 2000) paras 37-09 and 37-48: “It became usual for experts to detail the results of an examination before being asked as to their opinions founded thereon … . … In general an expert may give evidence in chief as to the grounds on which he has reached his opinion, and it may be said that, without the grounds, the opinion is valueless.” Indeed, it is clear that the practice of giving only the conclusion in chief is not only not customary, but is opposed to a line of authority which, while not citing Davie’s case, has arrived at conclusions consistent with and supportive of it.

The basal principle is that what an expert gives is an opinion based on facts. Because of that, the expert must either prove by admissible means the facts on which the opinion is based, or state explicitly the assumptions as to fact on which the opinion is based. If other admissible evidence establishes that the matters assumed are “sufficiently like” the matters established “to render the opinion of the expert of any value”, even though they may not correspond “with complete precision”, the opinion will be admissible and material: see generally Paric v John Holland Constructions Pty Ltd [1984] 2 NSWLR 505 at 509-510; Paric v John Holland Constructions Pty Ltd (1985) 59 ALJR 844 at 846. One of the reasons why the facts proved must correlate to some degree with those assumed is that the expert’s conclusion must have some rational relationship with the facts proved.

Thus one of Dixon J’s reasons in Bugg v Day (1949) 79 CLR 442 at 462 for criticising the reception of a motor repairer’s evidence that the speed of a taxi cab when it hit a motor cycle inspected by him was that it “plainly involved assumptions of fact that were not adverted to by the witness”. Latham CJ said at 456: “he had not been provided with data which would have been necessary to enable any person to form even an approximate estimate of the speed of either vehicle at the moment of the collision. He was not informed as to the weight of the taxi-cab or as to the distances, after the accident, of the two vehicles from the point of collision.”

A classic illustration of one type of case in which the principle applies is Ramsay v Watson (1961) 108 CLR 642. It shows that the “assumed” facts need not be itemised in an artificial way, but can be stated more informally. The High Court held that it was permissible for a doctor to narrate the history obtained from a patient as part of the foundation of the doctor’s opinion on the patient’s health, even though the narration was not admissible to prove the facts of the history unless some exception to the hearsay rule were satisfied. In the type of case of which Ramsay v Watson is an example, the ultimate opinion of the doctor will usually be based in part on his personal observation of the patient and in part on what the patient tells the doctor. Ramsay v Watson also contains the opinion of Dixon CJ, McTiernan, Kitto, Taylor and Windeyer JJ that if the history is not supported by admissible evidence, then the opinion “may have little or no value, for part of the basis of it is gone”. In fact, the evidence in Ramsay v Watson was not merely of “little or no value”, but inadmissible. The plaintiff sued for damages based on an allegation that Bright’s disease, from which he suffered, had been caused by lead poisoning incurred in his employment in the Government Printing Office. The defendant proved that 21 other employees had worked at the Government Printing Office, and a government medical officer testified that they did not have symptoms of lead poisoning. Counsel for the defendant attempted to elicit further evidence from the medical officer concerning what each employee told him of his past state of health. He made it clear that he did not intend to call the 21 men as witnesses. The questions were disallowed. The High Court held that the ruling was proper, “it having been apparent that the men would not be called”. Underlying the High Court’s conclusion must be the proposition that so massive a disconformity between the facts to be assumed on the basis of the 21 histories and the total failure to seek to prove them justified total rejection of the evidence.

One other important aspect of Ramsay v Watson is the following statement at 645: “That some medical witness should go into the box and say only that in his opinion something is more probable than not does not conclude the case. A qualified medical practitioner may, as an expert, express his opinion as to the nature and cause, or probable cause, of an ailment. But it is for the jury to weigh and determine the probabilities. In doing so they may be assisted by the medical evidence. But they are not simply to transfer their task to the witnesses. They must ask themselves ‘Are we on the whole of the evidence satisfied on a balance of probabilities of the fact?’. “ The jury cannot weigh and determine the probabilities for themselves if the expert does not fully expose the reasoning relied on.

An example of the importance of distinguishing the history given to and the opinion formed by a doctor is Steffen v Ruban [1966] 2 NSWR 622. A boy who had allegedly suffered brain damage called a psychiatrist, who gave evidence of what the boy and his mother told him. The boy did not give evidence and the mother’s evidence was cut short because of her distressed state. Jacobs JA (Wallace P and Asprey JA agreeing) said at 626: “… the effect of the plaintiff’s mother ceasing to give her account of his behaviour and of the plaintiff not being called, so that the jury could observe for themselves his current condition, is to make it important to scan carefully the medical evidence in order to make sure that as far as possible it is limited in its effect on the jury to matters of which the doctor gives direct evidence from his observations and matters upon which he expresses an opinion based on his observation. If his evidence is such that it is impossible to analyse and determine what are conclusions based on his own observation and what are conclusions based on what he has been told, then in such a case as the present one the danger of a mistrial becomes very great (cf. Ramsay v Watson (1961) 108 CLR 642, and Evans v Hartigan (1941) 41 SR (NSW) 179). I find Dr Bailey’s evidence such a confusion of observation, statement and opinion given with little precision but much lack of consistency that in the particular circumstances of this case, whether or not the amount of £18,500 is excessive, the verdict cannot stand. … I cannot be clear from Dr Bailey’s evidence whether he was expressing conclusions based on his own observations or based on what he had been told by the boy’s mother. If his conclusions were mainly based on what he had been told by the boy’s mother then there is no evidence from her that what she told the doctor was correct, and in the present case this is of vital importance. If any part of Dr Bailey’s evidence was sufficiently clearly based on his own observations or tests and not in whole or in part contradicted by other portions of his evidence that one could say that, despite deficiencies in proof of the history of the plaintiff, nevertheless the medical evidence was clear, there might be no occasion to interfere with the jury’s verdict. However, I find it quite impossible to say this on Dr Bailey’s evidence.” Underlying these observations is an assumption that the trier of fact must arrive at an independent assessment of the opinions and their value, and that this cannot be done unless their basis is explained.

In R v Turner [1975] QB 834 at 840 Lawton LJ said: “Before a court can assess the value of an opinion it must know the facts upon which it is based. If the expert has been misinformed about the facts or has taken irrelevant facts into consideration or has omitted to consider relevant ones, the opinion is likely to be valueless. In our judgment, counsel calling an expert should in examination in chief ask his witness to state the facts upon which his opinion is based. It is wrong to leave the other side to elicit the facts by cross-examination.”

A further illustration of the importance which the law attaches to the identification, whether formally or informally of the assumed facts, is R v Fowler (1985) 39 SASR 440 at 442. King CJ said: “It must be kept steadily in mind that the court (the jury in a jury trial) is the tribunal of fact and that it is no part of the function of a witness to decide what version or interpretation of the facts is to be accepted or rejected. The witness who expresses an opinion as to the likely or possible state of mind of the accused at a given time must give his opinion upon an assumed state of facts postulated to him or by him for that purpose. Strictly speaking it is not permissible for him to recount what he has been told, as distinct from what he assumes as the basis of his opinion, as that would result in hearsay material coming to the notice of the Court. The strictness of this rule is often relaxed in civil proceedings where there is no jury, as the judge is able to disregard the hearsay as non-probative and discount the opinion if the assumption of the witness as to the correctness of the hearsay material is not substantiated by admissible evidence. But adherence to the rule is of the utmost importance when the evidence is given before a jury. The position is somewhat different where a medical witness who has examined a person is called to express an opinion as to his mental or physical condition. In such a situation the history given by the patient and the very fact that he gives such a history is as much part of the material upon which the opinion is formed as the physical examination and is invariably allowed to be given in evidence by the medical witness. But even in that case what the patient has told the medical witness is not evidence of the truth of what is related, except so far as it may be admissible against the patient as an admission or may be admissible as a contemporaneous statement as to his sensations, and the validity of the opinions expressed will be affected if what is related is not substantiated by evidence.” At 443 he said: “The course which was sought to be adopted in the present case of asking the opinion of the witness as to the possible mental condition of the accused at the time of the alleged crime, based not upon assumed facts, but upon a reading of the whole of the evidence and the accused’s account of his drug ingestion, is not acceptable and such evidence cannot be admissible. It involves the expert in making his own unstated findings of fact and his own interpretation of them. The jury might arrive at different conclusions of fact and a different interpretation of the facts. Clearly a witness cannot be permitted to express his findings and interpretations of fact, and there would therefore be no way by which the jury could know whether the opinion could stand in the light of the jury’s view of the facts. If, therefore, evidence of opinion is to be adduced at the new trial as to the accused’s mental condition at the time of the killing deduced from his behaviour and ingestion of drugs, it is of the utmost importance that the assumptions of fact upon which the opinion is arrived at be clearly stated and that the evidence be confined to opinions expressed upon those stated assumed facts.”

In Holtman v Sampson [1985] 2 Qd R 472 at 474, D M Campbell, Macrossan and Thomas JJ said: “… it is a primary tribunal’s duty to find ultimate facts, and, so far as it is reasonably possible to do so, to look not merely to the expertise of the expert witness, but to examine the substance of the opinion expressed. But that is not to say that a tribunal may not accept the opinion of an expert witness. In cases where the experts differ, the lay tribunal will apply logic and commonsense to the best of its ability in deciding which view is to be preferred or which parts of the evidence are to be accepted.” Examining the substance of an opinion cannot be carried out without knowing the essential integers underlying it.

In Bell v F S & U Industrial Benefit Society Ltd (unreported, Supreme Court of New South Wales, 9 September 1987), McLelland J said that the importance of proving the facts underlying an opinion was that the absence of such evidence deprives “the court of an important opportunity of testing the validity of process by which the opinion was formed, and substantially reduces the value and cogency of the opinion evidence.”

In Lewis v R (1987) 88 FLR 104 at 123-124, Maurice J said: “Forensic evidence, especially if it goes to a vital issue implicating an accused person in the commission of an offence, may often have a prejudicial effect on the minds of a jury which far outweighs its probative value. The jury, being people without scientific training, may often be impressed by an expert’s qualifications, appointments and experience and the confident manner in which he expresses his opinions. And yet it ought not be left to such matters alone to provide a foundation for the jury making an assessment of the probative value of forensic evidence, particularly where there are conflicts in expert testimony, or where it is acknowledged that other experts of more or less equal distinction are unlikely to agree. For my part I think that whenever the Crown wishes to rely upon forensic evidence the prosecutor has a clear duty, not just to his client, the Crown, but to the trial judge and the jury to acquaint them, in ordinary language, through the evidence he leads, with those aspects of the expert’s discipline and methods necessary to put them in a position to make some sort of evaluation of the opinions he expresses. Where the evidence is of a comparatively novel kind, the duty resting on the Crown is even higher: it should demonstrate its scientific reliability. It is not an answer to considerations that dictate these things to be done to say the defence may draw it out in cross-examination; that is an abdication of the Crown’s primary function in a criminal prosecution. There is a tendency amongst academics, professionals and others who develop skills in a particular area to mystify their field, often by the use of what seems to the outside to be arcane language. It is the role of a prosecutor to strip forensic evidence of its mystery so far as is possible; trial by expert must never be allowed to take the place of trial by jury. The inability to articulate the principal tenets that need to be understood, to describe in ordinary language the methods used and the reasons that point to a particular conclusion, these are the hallmarks of unreliable science and the not-so-qualified expert.” These words were applied in R v Lucas [1992] 2 VR 108 at 116-117 by Hampel J. Though they were used in the context of criminal cases, they have application in civil cases as well.

In Trade Practices Commission v Arnotts Ltd (No 5) (1990) 21 FCR 324 at 327 Beaumont J approved the following remarks of Wigmore on Evidence , Vol II (Chadbourn revision, 1979), para 672, pp 933-934: “1. Testimony in the shape of inferences or conclusions always rests on certain premises of fact . That which has been called observation, serving as the basis of belief in matters directly cognizable by the senses - as, the facts of an affray, a conversation, a trespass, and the like - is here replaced by what may be called a consideration of the premise. If the witness has not considered or had in mind these premises, his inference or opinion is good for nothing. 2. These premises , a consideration of which is essential to the formation of the conclusion or opinion, must somehow be supplied to the jury by testimony . The same witness may supply both premises or conclusion; or one witness may supply the premises and another the conclusion. The two are not necessarily connected. 3. If the latter method is chosen, and a witness is put forward to testify to the conclusion, the premises considered by him must be expressly stated, as the basis of his conclusion ; otherwise, since his conclusion rests for its validity upon a consideration of the premises, if those premises are not made to accompany the conclusion, the tribunal might be accepting a conclusion for which the witness had considered premises found by the tribunal not to be true. 4. Hence, the premises must be stated hypothetically in connection with the conclusion ; then, by other testimony, the material for determining the truth of the assumed premises may be furnished to the tribunal. The key to the situation, in short, is that there may be two distinct subjects of testimony - premises, and inferences or conclusions; that the latter involves necessarily a consideration of the former; and that the tribunal must be furnished with the means of rejecting the latter if upon consultation they determine to reject the former, ie of distinguishing conclusions properly founded from conclusions improperly founded.”

Beaumont J also quoted from Gordon J Samuels, “Problems Relating to the Expert Evidence in Personal Injury Cases” in (ed) Harold H Glass, Seminars on Evidence (Law Book Co Ltd, 1970) p 145: “Clearly, the facts which the witness is assuming must be made clear to the jury. They must know upon what premises the conclusion is based. This is necessary not only to render the conclusion useful but to impeach it if the premises be not established. In what form then may the premises be conveyed to the witness? First, may the witness be asked - ‘Upon all the evidence in the case what is your opinion as to X’? A question in this form is, it is suggested, clearly objectionable. First, because it renders it impossible for a jury to determine whether the opinion is based upon facts which have been proved, or indeed to determine at all upon what facts it is based. Second, it permits and encourages the witness to select for himself which of the evidence he accepts and which he rejects. The evidence of one witness whose testimony is furnished to the expert as part of his data may itself be internally conflicting, and this apart from the discrepancies between the evidence of witnesses called in the same interest.”

After also referring to authorities including R v Turner [1975] QB 834, Paric v John Holland (Constructions) Pty Ltd [1984] 2 NSWLR 505 at 509-510, Paric v John Holland (Constructions) Pty Ltd (1985) 59 ALJR 844 at 846 and R v Fowler (1985) 39 SASR 440 at 443, Beaumont J rejected the evidence of an expert who had attended or read the transcript of the whole hearing and had read all the exhibits and who then commented on particular allegations in the Statement of Claim. He said at 330: “In my opinion, these authorities establish that there is a rule of evidence at common law that, except in a straight-forward, uncomplicated case, where the facts are admitted and readily identified, the opinion of an expert is admissible only where the premises, that is to say, the facts, upon which his or her opinion is based, are expressly stated. It follows that, in a complex case, where facts are not readily identifiable, it is not permissible to put the whole of the transcript and documentary evidence to the witness en bloc. This is complex litigation and the facts in respect of which Dr Williams purported to express his opinion were not admitted by the respondents. Indeed, the facts, and the proper inferences or conclusions to be drawn from the facts contended for by the Commission, were vigorously disputed by the respondents over the many months of this litigation. In those circumstances, it is impossible for the court to know what facts Dr Williams had in mind when expressing his views. This objection to his evidence is not a mere technicality nor is it only a rule to be applied in jury trials. True, some of the authorities refer to the jury, but the rule is of general application. In complicated litigation, there are sound reasons of policy which support a rule that the premises considered by the expert should be expressly stated rather than left to speculation. It is preferable that these matters be clarified when the witness is examined in chief rather than leave room for argument later as to exactly what matters the expert had in his mind when expressing his conclusions.”

An appeal against the rejection of the expert’s evidence failed. On appeal ( Arnotts Ltd v Trade Practices Commission (1990) 24 FCR 313) the Full Federal Court (Lockhart, Wilcox and Gummow JJ) repeated various of Beaumont J’s citations. They also referred (1990) 24 FCR 313 at 350-351 to Sir Richard Eggleston, Evidence, Proof and Probability (2nd ed, 1983) pp 147-148: “Assuming that the matter is one on which only an expert can express an opinion, what sort of opinion may he give, and on what material can it be based? It is often said that an expert cannot give an opinion as to the ultimate fact that the court has to decide. This is inaccurate, as experts, especially valuers, often give evidence as to the ultimate fact, and in many cases the question whether that fact exists can be answered only by experts … What the rule really means is that an expert must not express an opinion if to do so would involve unstated assumptions as to either disputed facts or propositions of law. Thus an expert who says ‘In my opinion this accident was caused by … ‘ in a case where the facts are disputed is assuming the right to make a decision as to which of the parties is telling the truth, and is therefore usurping the function of the tribunal. Similarly, if a valuer is called in a case where the ‘unimproved value’ of a property is in issue, and there is uncertainty as to the meaning of the term as a matter of law, the expert should not say ‘In my opinion the unimproved value is …’ without stating on what interpretation of the term his opinion is based. In general, where there is uncertainty of either description, the opinion should be based on hypothetical facts, clearly stated. As to the material on which the expert opinion can be based, just as the non-expert who is allowed to express an opinion does so on the basis of experience, so can the expert base his opinion on his experience, without having to prove by admissible evidence all the facts on which the opinion is based. Accordingly, a valuer can base his opinion on comparable sales of property, without having to call witnesses to prove the facts relating to the sales. An experienced valuer will in the course of a lifetime accumulate a mass of material about sales, from his own practice, from journals, from newspaper reports, and from discussion with his fellow practitioners, much of which he will be unable to recall, but which enables him to express an opinion more accurately than one who has examined only the facts regarding the sales in the area. But if he wishes to cite a particular instance to the court, for example, where there is an adjoining property that has recently been sold, evidence must be given by someone who can swear to the facts relating to the sale.” The Full Federal Court also quoted from Sir Richard Eggleston’s opinions on the role of the expert as advocate (at p 154): “This is the area in which experts find themselves in the greatest trouble. It is of course not permissible for the expert to take over the role of advocate from counsel in the case - the law does not allow unqualified people to act as barristers, except in special courts like the industrial tribunals or the small claims courts. But the expert has a legitimate role of advocacy in that, having expounded to the tribunal the rules applicable to the case (these may not even be in dispute), his evidence may then consist of argument as to the conclusions that should be drawn from the facts, interpreted in the light of those rules. The difficulty arises because the expert often finds it difficult to distinguish between argument on the assumption that the ‘facts’ put forward by his side are the correct ones, and telling the judge or jury which facts they should accept as true. If he makes his assumption clear, there is no objection to his arguing what the consequences of accepting those assumptions should be; but he is not to do the jury’s fact-finding for it, where this depends on accepting one or the other set of contradictory witnesses.” (It may be that the legitimate sphere in which the expert can function as advocate has shrunken to some extent since Sir Richard Eggleston’s days. Practice Note 104, para 2, provides: “An expert witness’s paramount duty is to assist the court impartially. That duty overrides the expert witness’s obligation to the engaging party. An expert witness is not an advocate for a party.” See also ULV Pty Ltd v Scott (1990) 19 NSWLR 190 at 205.)

The Full Federal Court in Arnotts Ltd v Trade Practices Commission (1990) 24 FCR 313 criticised the expert’s evidence for various reasons. One answer: “depended upon Dr Williams’ evaluation of the whole of the evidence known to him. He did not identify the particular facts upon which he based his opinions, nor his processes of reasoning. It may be assumed that Dr Williams had regard to the whole of the evidence given to that stage of the hearing, because he said that he had heard or read it all. But there was no way of knowing what parts of that evidence he accepted as correct or what weight he gave to particular aspects of it.” The Full Federal Court then said (at 349): “The events of this case underline the importance of the principle that an expert witness must identify the facts assumed in his or her opinion. After Dr Williams left the witness box, a considerable amount of other material, both oral and documentary, was admitted into evidence. Without knowledge of the basis of Dr Williams’ conclusions, the trial judge had no way of knowing whether that additional material would have affected Dr Williams’ views.” The court said (at 352): “The fundamental problem about his evidence is that he attempted to act as advocate without making his assumptions clear. He did not assume a set of identified facts, consistent with those contended for by the appellants. Rather, he told the judge what facts he should accept.” The court opposed any departure from the rule requiring the disclosure of expert assumptions on two grounds (at 352): “The first is the very justification advanced by counsel, the difficulty in predicting ‘the permutations and combinations necessary to cover all possible findings by the Court’. If an economist were permitted to express opinions upon the effect of the evidence given, without identifying the facts which he or she assumed for the purpose of those opinions, it would be impossible for the Court to know how to apply that evidence. One of the permutations or combinations may have rendered the opinion inapplicable, in the expert’s eyes, but the Court would never know. Secondly, as this case indicates, the course urged by counsel would serve only to prolong trials.” The court described as “illegitimate” the “use of an expert witness to filter the facts, asking the witness to hear or read all the evidence and then express factual conclusions …”

In National Justice Compania Naviera SA v Prudential Assurance Co Ltd (“The Ikarian Reefer”) [1993] 2 Lloyd’s Rep 68 at 81-82 Cresswell J set out a list of duties and responsibilities of expert witnesses in civil cases as follows: “1. Expert evidence presented to the Court should be, and should be seen to be, the independent product of the expert uninfluenced as to form or content by the exigencies of litigation … . 2. An expert witness should provide independent assistance to the Court by way of objective unbiased opinion in relation to matters within his expertise … . An expert witness in the High Court should never assume the role of an advocate. 3. An expert witness should state the facts or assumption upon which his opinion is based. He should not omit to consider material facts which could detract from his concluded opinion. 4. An expert witness should make it clear when a particular question or issue falls outside his expertise. 5. If an expert’s opinion is not properly researched because he considers that insufficient data is available, then this must be stated with an indication that the opinion is no more than a provisional one … . In cases where an expert witness who has prepared a report could not assert that the report contained the truth, the whole truth and nothing but the truth without some qualification, that qualification should be stated in the report … . 6. If, after exchange of reports, an expert witness changes his view on a material matter having read the other side’s expert’s report or for any other reason, such change of view should be communicated (through legal representatives) to the other side without delay and when appropriate to the Court. 7. Where expert evidence refers to photographs, plans, calculations, analyses, measurements, survey reports or other similar documents, these must be provided to the opposite party at the same time as the exchange of reports … .“ While some of these matters have an ethical dimension, taken together they point to the need for the trier of fact to be fully informed of the reasoning process deployed in arriving at the expert’s opinions. Cresswell J’s list has been influential both in causing rules of court to be devised in this and other jurisdictions to control expert evidence and in later judicial pronouncements. Thus in Clough v Tameside and Glossop Health Authority [1998] 2 All ER 971 at 977 Bracewell J said: “It is only by proper and full disclosure to all parties, that an expert’s opinion can be tested in court: in order to ascertain whether all appropriate information was supplied and how the expert dealt with it. It is not for one party to keep their cards face down on the table so that the other party does not know the full extent of information supplied.” This implies that not only must the appropriate information be supplied, but that the expert must reveal the whole of the manner in which it was dealt with in arriving at the formation of the expert’s conclusions.

In Pownall v Conlan Management Pty Ltd (1995) 12 WAR 370 at 389-90 Anderson J said: “It goes without saying that in order to furnish an opinion about the profitability or net cash flow of the project, it is necessary to make assumptions about the cost of operations, including the mine operating costs, the cost of crushing and screening, the cost of transportation, the cost of ship loading and so on. In order for the opinion to be admissible in evidence, it is necessary that the assumptions made about such matters be satisfactorily proved by admissible evidence. … These were critical elements of the opinion, the excision of which would leave the opinion without sufficient content. Putting that another way, it is apparent from the report as a whole that if the objectionable material was excluded from it Mr Adam could not have come to a rationally based opinion about the value of the tenements. Mr Adam gave oral testimony and attempts were made to lead from him evidence that would show that he had personally verified the data relied on for his estimates or had direct knowledge of the matters relied on. In my opinion, his evidence did not go that far. If anything it underlined the fact that he truly had relied on a range of material reported to him or provided by others. No doubt he treated the data he was given with appropriate circumspection and accorded to it more or less reliability according to his own views about the quality of it and of its provenance and no doubt in doing so, he called upon his own personal experience. Whilst in one sense this constitutes bringing his own judgment to bear on the task of valuation, I do not think it overcomes the fundamental difficulty. Expert opinion is to be judged like any other evidence. It must be comprehensible and reach conclusions that are rationally based. The process of inference that leads to the conclusions must be stated or revealed in a way that enables the conclusions to be tested and a judgment made about the reliability of them. This requirement is not satisfied by evidence from an expert which says, in effect: ‘I have examined the costings and estimates made by others and on the strength of my own expertise and experience in the field I believe them to be reasonable.’ Such a forensic device overlooks the most important rule that it is for the court to judge the reliability of evidence given in support of the case. If an opinion relies on facts that must be proved or assumptions that must be verified, it is to the court that they must be proved and verified, not to the expert witness.” Ipp J (Malcolm CJ concurring), after referring in particular to R v Turner [1975] QB 834 at 840, Ramsay v Watson (1961) 108 CLR 642 and Steffen v Ruban [1966] 2 NSWR 622, reached similar conclusions.

In Bollock v Wellington (1996) 15 WAR 1 at 3 Anderson J said: “Before an expert medical opinion can be of any value the facts upon which it is founded must be proved by admissible evidence and the opinion must actually be founded upon those facts …” He then said at 3-4, citing Steffen v Ruban : “As with any other evidence, expert opinion must be comprehensible and the conclusions reached must be rationally based. A court ought not to act on an opinion, the basis for which is not explained by the witness expressing it … None of these requirements is satisfied, when all that the medical expert says is ‘I have examined this patient and from what I know about plant operation I think he can drive a D10 bulldozer on production work’.” He also said at 4, citing Pownall v Conlan Management Pty Ltd (1995) 12 WAR 370 at 390: “Unless the process of inference by which an opinion is reached is expressed in a manner which permits the conclusions to be scrutinised and a judgment made as to its reliability, the opinion can carry no weight … .”

In R v Kotzmann [1999] 2 VR 123 at 135 Callaway JA said that it was desirable for juries to be directed that “expert evidence is no better than the facts on which it is based, that it is for the jury to be satisfied of the facts in issue at the trial and that ultimately it is their opinion that counts”. At 156 Batt JA said that even where the expertise of the witnesses is not questioned, and even where their evidence is contradicted or substantially contested, there should as well be a direction that “the weight to be given to the opinions of experts is to be assessed in the same way as the weight to be given to the evidence of other witnesses”. This cannot be done unless the intellectual basis of the opinion is laid out.

The English and Australian authorities so far referred to analysed the decisions at common law. Expert evidence in this State is now primarily regulated by the Evidence Act 1995 (NSW). The relevant provisions are in ss 76-80: “76. Evidence of an opinion is not admissible to prove the existence of a fact about the existence of which the opinion was expressed. 77. The opinion rule [i.e., s 76] does not apply to evidence of an opinion that is admitted because it is relevant for a purpose other than proof of the existence of a fact about the existence of which the opinion was expressed. 78. The opinion rule does not apply to evidence of an opinion expressed by a person if: (a) the opinion is based on what the person saw, heard or otherwise perceived about a matter or event; and (b) evidence of the opinion is necessary to obtain an adequate account or understanding of the person’s perception of the matter or event. 79. If a person has specialised knowledge based on the person’s training, study or experience, the opinion rule does not apply to evidence of an opinion of that person that is wholly or substantially based on that knowledge. 80. Evidence of an opinion is not inadmissible only because it is about: (a) a fact in issue or an ultimate issue; or (b) a matter of common knowledge.”

In HG v R (1999) 197 CLR 414 at [39]-[44] Gleeson CJ construed these provisions as enacting some of the central elements of the common law just discussed. “[39] An expert whose opinion is sought to be tendered should differentiate between the assumed facts upon which the opinion is based, and the opinion in question [ Ramsay v Watson (1961) 108 CLR 642; Arnotts Ltd v Trade Practices Commission (1990) 24 FCR 313 at 347-348]. Argument in this Court proceeded upon the basis that it was possible to identify from Mr McCombie’s written report some facts which he either observed or accepted, and which could be distinguished from his expressions of expert opinion. Even so, the provisions of s 79 will often have the practical effect of emphasising the need for attention to requirements of form. By directing attention to whether an opinion is wholly or substantially based on specialised knowledge based on training, study or experience, the section requires that the opinion is presented in a form which makes it possible to answer that question. [40] Mr McCombie’s report referred to a number of matters he took into account in reaching the conclusions he expressed: things he was told by the complainant, by her mother, and by the general practitioner who referred the complainant for assessment; his training as a psychologist; his experience in counselling victims of sexual abuse; and his knowledge of patterns of behaviour of disturbed children. It is not in dispute that psychology is a field of specialised knowledge, and that a psychologist may be in a position to express an opinion based on his or her specialised knowledge as a psychologist. However, the witness had to identify the expertise he could bring to bear, and as Clark v Ryan [(1960) 103 CLR 486] illustrates, his opinions had to be related to his expertise. [41] If all that Mr McCombie had said was that, based on his study, training and experience, he considered that the behaviour of the complainant during 1992 and 1993, as recounted to him by others, appeared to be inconsistent with her having been sexually abused during that time … , then that might have been one thing. It would have required identification of the facts he was assuming to be true, so that they could be measured against the evidence; and it would have required or invited demonstration or examination of the scientific basis of the conclusion. … What defence counsel wanted was evidence of his opinion that, although the complainant had been abused, the abuse had occurred back in 1987 when, for a period of a month, she was in the custody of her father, and that it was the father who was the abuser. That opinion was not shown to have been based, either wholly or substantially, on Mr McCombie’s specialised knowledge as a psychologist. On the contrary, a reading of his report, and his evidence at the committal, reveals that it was based on a combination of speculation, inference, personal and second-hand views as to the credibility of the complainant, and a process of reasoning which went well beyond the field of expertise of a psychologist. He did not put to the complainant, for her comment, the suggestion that she had been abused by her father; the complainant told him she could not remember her father. He does not appear to have considered or investigated the possibility of abuse by some third party. He appears to have inferred, for no apparent reason, that the words ‘stop it daddy’, attributed to the complainant by her mother, referred to sexual as distinct from some other form of abuse. [42] Logically, there were a number of competing possibilities. The complainant may have been sexually abused by nobody; she may have been abused as she claimed, by the appellant; she may have been abused by her father; she may have been abused by both her father and the appellant; she may have been abused by some person or persons unknown. It was not demonstrated, and it is unlikely, that it is within the field of expertise of a psychologist to form and express an opinion as to which of those alternatives was to be preferred. [43] To paraphrase what was said by Dixon CJ in Clark v Ryan [(1960) 103 CLR 486 at 492] about the expert witness in that case, the evidence the defence sought to lead from Mr McCombie really amounted to putting from the witness box the inferences and hypotheses on which the defence case wished to rely. [44] This was not a trial by jury, but in trials before judges alone, as well as in trials by jury, it is important that the opinions of expert witnesses be confined, in accordance with s 79, to opinions which are wholly or substantially based on their specialised knowledge. Experts who venture ‘opinions’ (sometimes merely their own inference of fact), outside their field of specialised knowledge may invest those opinions with a spurious appearance of authority, and legitimate processes of fact-finding may be subverted. The opinions which Mr McCombie was to be invited to express appear to provide a good example of the mischief which is to be avoided.”

In short, if evidence tendered as expert opinion evidence is to be admissible, it must be agreed or demonstrated that there is a field of “specialised knowledge”; there must be an identified aspect of that field in which the witness demonstrates that by reason of specified training, study or experience, the witness has become an expert; the opinion proffered must be “wholly or substantially based on the witness’s expert knowledge”; so far as the opinion is based on facts “observed” by the expert, they must be identified and admissibly proved by the expert, and so far as the opinion is based on “assumed” or “accepted” facts, they must be identified and proved in some other way; it must be established that the facts on which the opinion is based form a proper foundation for it; and the opinion of an expert requires demonstration or examination of the scientific or other intellectual basis of the conclusions reached: that is, the expert’s evidence must explain how the field of “specialised knowledge” in which the witness is expert by reason of “training, study or experience”, and on which the opinion is “wholly or substantially based”, applies to the facts assumed or observed so as to produce the opinion propounded. If all these matters are not made explicit, it is not possible to be sure whether the opinion is based wholly or substantially on the expert’s specialised knowledge. If the court cannot be sure of that, the evidence is strictly speaking not admissible, and, so far as it is admissible, of diminished weight. And an attempt to make the basis of the opinion explicit may reveal that it is not based on specialised expert knowledge, but, to use Gleeson CJ’s characterisation of the evidence in HG v R (1999) 197 CLR 414, on “a combination of speculation, inference, personal and second-hand views as to the credibility of the complainant, and a process of reasoning which went well beyond the field of expertise” (at [41]).

That statement of the law corresponds with the views of Black CJ, Cooper J and Emmett J in Ocean Marine Mutual Insurance Association (Europe) OV v Jetopay Pty Ltd [2000] FCA 1463 at [21]-[23]: “[21] The primary judge considered that it was permissible to examine the reports and draw inferences from the form and contents of them. His Honour considered that it was permissible to take into account: · the factual context in which a report was produced; · the description and designation of the person making the report; · the contents and language of the report and the nature of the assertions made in it; · the form of the report; · the expressed qualifications of the person making it as set out in the report. [22] However, it is not permissible to conclude from those matters alone that an author of a report has any specialised knowledge, except to the extent that the report states (or it otherwise appears from admissible evidence) what that knowledge is. Nor is it permissible, by reason of those matters alone, to conclude that any specialised knowledge that the author of a report has is based on any training, study or experience of the author. Thus, it is not permissible to conclude, simply because a person expresses an opinion on a particular subject, referring to particular technology, that that person has any specialised knowledge in relation to that subject. There must be specific evidence as to specialised knowledge of the person in relation to that subject and as to the training, study or experience upon which that specialised knowledge is based. [23] The further requirement that an opinion be based on specialised knowledge would normally be satisfied by the person who expresses the opinion demonstrating the reasoning process by which the opinion was reached. Thus, a report in which an opinion is recorded should expose the reasoning of its author in a way that would demonstrate that the opinion is based on particular specialised knowledge. Similarly, opinion evidence given orally should be shown, by exposure of the reasoning process, to be based on relevant specialised knowledge.” The last quoted paragraph was applied by Einstein J in Idoport Pty Ltd v National Australia Bank Ltd [2001] NSWSC 123 at [19]. Evidence not complying with the principles described in it might be inadmissible as irrelevant (s 56(2)), as not complying with s 79, or on discretionary grounds (s 135). However, no objection was taken to Professor Morton’s evidence, so the only issue for this Court is its weight.

There is no doubt about Professor Morton’s authority, experience, qualifications and skill. It is also the case that Professor Morton’s report is quite lengthy and detailed. But, given that the court is not obliged to take the opinion of an expert as conclusive even though no other expert is called to contradict it, can it be said that Professor Morton’s report goes beyond a series of oracular pronouncements? Does it usurp the function of the trier of fact? More vitally, did it furnish the trial judge with the necessary scientific criteria for testing the accuracy of its conclusions? Did it enable him to form his own independent judgment by applying the criteria furnished to the facts proved? Was it intelligible, convincing and tested? Did it go beyond a bare ipse dixit ? Did it contain within itself materials which could have convinced the trial judge of its fundamental soundness?

It is significant that the trial judge himself did not identify any scientific criteria within the report for testing the accuracy of its conclusions. The trial judge summarised Professor Morton’s evidence ([125]-[134]) and accepted his conclusions ([203]-[204]). But he did not analyse Professor Morton’s conclusions. Perhaps he did not feel the need to do so, in view of the fact that no expert was called in opposition to Professor Morton, and in view of the fact that the cross-examination of Professor Morton was not lengthy. However, it remains the case that the trial judge did no more than accept the conclusions as they were stated.

In the course of argument on the appeal, attention tended to be directed to particular aspects of Professor Morton’s evidence in isolation. Though Professor Morton’s views often go to ultimate issues, they are not on that ground inadmissible: Evidence Act 1995 (NSW) s 80. However, even though Professor Morton’s evidence was uncontradicted, the trial judge was not bound to accept it, and nor is this Court, particularly where it was on ultimate issues: Brodie v Singleton Shire Council (2001) 75 ALJR 992 at [355] per Callinan J. Counsel for the plaintiff correctly said that an assessment of the merits of Professor Morton’s evidence called for consideration of it in detail and as a whole.

The first problem in Professor Morton’s evidence is that it is difficult to gather, either from Professor Morton’s report or from his cross-examination, what significance the coefficients of friction had in his thinking. He said that a minimum value of 0.4 for the dynamic coefficient of friction of a surface when tested with 4S rubber was set as a minimum value by AS3661.1:1993. He did not annex or exhibit that standard, and the standard is not in evidence on any basis, so that it is not possible to assess the context of that item of information passed on by Professor Morton or the reasoning underlying it. It is possible for one expert to adopt statements made in scientific works as part of his or her own testimony, but bare references to particular propositions carry no weight unless their basis is explained.

Professor Morton then said that “a floor satisfying this requirement is not necessarily safe, and particularly not for use by other types of footwear or under other conditions”. If so, why did AS3661.1:1993 select 0.4 as a standard for determining when a floor is slip-resistant?

Professor Morton said that the same position prevailed for BS5395 as for AS3661.1:1993, but that standard is not in evidence either, so that its context and reasoning cannot be assessed.

Professor Morton then said: “Whilst there are no universally agreed standards for floor friction it is usually accepted that dynamic friction coefficients below 0.4 are unsafe whereas above 0.5 they are safe.” He did not say who the persons were who shared this usual acceptance. He did not say why they, or he, had these views. Nor did he offer enlightenment as to the shadow land occupied by dynamic friction coefficients between 0.4 and 0.5. Further, this evidence appeared to be somewhat qualified in cross-examination. There Professor Morton said: “0.4 is commonly adopted”, and “above that it is safe”. He appeared to ascribe the figure of 0.5 for a reasonably safe surface to only “one or two people” and not to the larger number implicit in the phrase “usually accepted”.

The essential difficulty is that the significance of differences between 0.34, 0.35, 0.4 and 0.5 as coefficients of dynamic friction were never explained. On one view of Professor Morton’s evidence, there would be liability if the result of 0.39 were achieved, but not if 0.4 were achieved. The difference between 0.34 and 0.4 is not great mathematically, but whether it was crucial must depend on scientific issues of which the trial judge was told nothing.

A second difficulty in Professor Morton’s evidence is that he appeared to say that if a person descending stairs were not wearing high heels, the heel of that person would be placed on each step first. His evidence was: “Q. Does it make a difference whether the tip or sole of her foot touched stairs? A. It does make a difference. In the exceptional circumstances of someone wearing high heels the toe goes down followed by the heel. Q. But it may be that she did that? A. No, I do not accept that. The toe goes down, first, unless one is wearing high heels and then the heel cannot be placed on the step first.” (In saying this he appeared to be doing what Cussen J in R v Parker [1912] VLR 152 at 159 and Dixon J in Clark v Ryan (1960) 103 CLR 486 at 491 reprobated in experts, namely, attempts “to formulate their empirical knowledge as a universal law”.) The plaintiff’s shoes did not have high heels. Professor Morton rejected the cross-examiner’s proposition that the plaintiff put her toe down, “followed by the heel”. Hence his view seems to have been that her heel was placed on the stairs first. Professor Morton also said that the heel of the shoe in question was less smooth than the sole. Professor Morton did not offer an opinion as to whether, if the plaintiff slipped, it was her heel which slipped, or her sole, or both. Yet the dynamic coefficient of the heel recorded in Table 3 is 0.53, well above both 0.4 and 0.5, and not far short of the dynamic coefficient of 0.57 for 4S rubber, which AS3661.1:1993 selects as the touchstone for safety provided the value is greater than 0.4. Further, the dynamic coefficient of the heel on smooth concrete recorded in Table 4 is 0.5. Professor Morton did not explain how these circumstances fitted in with Professor Morton’s conclusions about slipperiness. In particular, he did not explain what the relevance is of a dynamic coefficient of friction of the plaintiff’s sole on the stairs of 0.34 when, according to Professor Morton, the heel, with a figure of 0.53, landed first. If the 0.34 figure for the sole in some way negates the safety implicit in the heel figure of 0.53, how it does was not explained. If the operation of the two parts of the shoe in combination is different from the operation of each part separately, that operation was not explained, and if that operation depends on separate testing, there is no evidence that that separate testing was carried out. Similar queries arise in relation to the figures for the frictional coefficients of the shoes on smooth concrete recorded in Table 4.

A third difficulty arose in the following way. At the end of Professor Morton’s re-examination the trial judge asked Professor Morton some questions about Table 3 as follows: “Q. I have had a look at the shoe and you have different figures for the sole and the heel of the shoe. I am a lay person of course in regard to this. I can only look at the shoe as it now is, but as it now is the heel seems to have a ridge pattern, a pattern of ridges across it? A. That’s right. Q. Whereas the sole appears to be smoother? A. Yes. Q. I take it that that has something to do with the different results you have come to? A. That would be one contributory fact. But the two surfaces are quite different in area so the pressure exerted on the heel would be greater per unit area on the sole. I think most have contributed. You note in Table 4 there are differences between the sole and heel and on every surface -- Q. The greater weight on the heel less tendency? A. There is a greater pressure, that is, the force is concentrated over a smaller area and that may have had an effect as well but the difference of the sole and heel carries through to all pedestrian surfaces that I test. Q. The heel is less likely to slip? A. Yes. FURTHER CROSS-EXAMINATION CRANITCH: Q. I may be at a misapprehension here. The coefficient of friction is not dependent on the surface? A. Normally not. Q. The smaller diameter of the heel thereby increasing coefficient of friction really does not hold water, does it? A. As I say, that statement you just made independent of area is usually the case but not invariably so. Q. Why is the case here? A. I don’t have an answer. All I can point to is the observed fact.” The trial judge said of this evidence: “Professor Morton was not really shaken in cross-examination (except at one stage when he fleetingly seemed to suggest that a coefficient of friction could depend on the pressure exerted on a surface) ….” To the lay mind, the “pressure exerted on a surface” might be thought to be a product of the factors of weight applied and the area to which it is applied. In paragraph 2 of his report Professor Morton said: “The usual measure of ‘slipperiness’ is its inverse, the coefficient of friction. This is the sideways force needed to cause an object to slide on a surface, expressed as a ratio to its weight - heavier objects naturally need more force. The usefulness of the coefficient is that it does not normally depend on the weight of the object and is thus a genuine measure of the surface properties.” The relationship between the proposition that “heavier objects … need more force” and the proposition that the coefficient does not “normally depend on the weight of the object” is not explained. Nor is the relationship between the proposition that the coefficient of friction is the ratio between sideways force and weight and the proposition that the coefficient does not “normally depend on the weight of the object”. Nor is the relationship between the statement in paragraph 4.4.2 that the particular method of testing selected by Professor Morton is preferred by him because of the possibility it provides for investigating “variations in … vertical load” and the proposition that the coefficient does not “normally depend on the weight of the object”. In relation to the trial judge’s comment on the evidence, it is not the case that Professor Morton “fleetingly seemed to suggest that a coefficient of friction could depend on the pressure exerted on a surface”: first, he did not seem to suggest it, he did suggest that it “may have had an effect”; and, secondly, the suggestion was not fleeting, but rather was adhered to at least in some cases in the second last answer quoted above. As is the case with other parts of the transcript of Professor Morton’s evidence, there is some doubt as to whether the questions and answers were all fully and accurately recorded, but the passages of evidence set out in this paragraph create further difficulties in understanding the scientific basis of Professor Morton’s opinions. In short, Professor Morton did not expect the smoothness of the sole compared to the ridge pattern on the heel to make a large difference which would explain the different coefficients observed; he pointed out that those differences existed for every surface in Table 4 as well as on the fire stairs used in Table 3; he said a possible reason was the greater pressure coming from the heel; he adhered to that as an exception to what “is usually the case”; the trial judge found this suggestion to be an instance where Professor Morton was “shaken”, albeit fleetingly; neither the evidence nor the trial judge explained Professor Morton’s position intelligibly.

Despite the length of Professor Morton’s report (21 pages), the heart of it consists of the figures in Table 3 for the plaintiff’s shoes, as analysed in paragraph 4.4.4; in particular, the assertion in paragraph 4.4.4: “for … common synthetic sole materials such as those used in Ms Sprowles’ shoes the treads are sufficiently slippery to be dangerous … .” That in turn leads to the observation in paragraph 5 that “the level of grip afforded is below that needed for a reliable margin of safety”. The reason why the treads were regarded by Professor Morton as dangerous and the level of grip below a reliable margin of safety is said to rest on the figure of 0.4 set out in AS3661.1:1993 and BS5395 referred to in paragraph 3.6. The significance of the figure of 0.4 is not explained. Paragraph 3.6 concludes with the statement: “Frictional properties of floors are highly dependent on the nature of the footwear used and the extent and nature of contamination which may be present. Grip requirements may depend also on the actions being undertaken on the surface in question (dancing, running, descending stairs etc.). Reliance therefore has to be placed on the opinion of suitably qualified individuals in the assessment of the adequacy of frictional grip of surfaces, given the circumstances applying to any particular situation. I believe that as a result of my extensive experience and qualifications in this field I am well equipped to provide a reliable opinion as to the safety of the stair treads in the present case.” That observation may well be correct. But what propositions in the laws of physics and what aspects of Professor Morton’s experience underpin the figure of 0.4 in paragraph 3.6 and the conclusions just quoted from paragraphs 4.4.4 and 5.1 are not revealed at any point.

In short, the report turns on a syllogism: (a) all surfaces having a dynamic coefficient of friction of less than 0.4 (or perhaps 0.5) are unsafe; (b) these stairs had a dynamic coefficient of friction of 0.34 for the plaintiff’s shoe sole; (c) therefore these stairs were unsafe. The basis of step (a) was not exposed. And the reason why step (b) existed when a figure of 0.53 for the shoe heel was recorded was not explained clearly. At the trial the defendant did not explicitly challenge Professor Morton’s reasoning in the manner set out above. So far as step (a) is concerned, the cross-examiner did, though, raise doubt as to whether the figure was 0.3, 0.4 or 0.5. So far as step (b) is concerned, the trial judge and the cross-examiner between them exposed the unclarity in Professor Morton’s explanation. While the line of attack which the defendant employed in cross-examination of Professor Morton and the line of argument the defendant employed in final address below do not correspond with the criticisms of Professor Morton just made, it is open to this Court not to accept his conclusions. Neither the acceptance of those conclusions by the trial judge nor their rejection on appeal turn on any issue of credibility. The basis of Professor Morton’s reasoning was sufficiently challenged at trial to permit the trial judge’s conclusion that the defendant was in breach of duty to be reversed. The defendant did not advance on appeal the arguments against acceptance of Professor Morton’s conclusions set out above. However, in the course of interchanges during oral submissions the possibility was made plain that the court would not accept expert evidence, including the expert evidence of Professor Morton, even if the parts which depended on acceptance of the plaintiff’s evidence stood (transcript pages 23 line 58-24 line 10, 24 lines 43-50 and 30 lines 6-29). Counsel for the plaintiff said in oral address: “when the court reads Professor Morton’s report and his oral evidence …, the case is made out because he formed the view that these stairs were slippery”. Implicit in the invitation to read Professor Morton’s evidence and to arrive at that conclusion is an acceptance of the possibility that the court might read the evidence and reject his conclusion.

At the trial there was in effect a collision between two bodies of evidence called before the trial judge. One was Professor Morton’s report. The other was the lay evidence that no problems had been experienced by the plaintiff, Mr Firth or apparently anyone else in relation to the stairs apart from the plaintiff’s fall. The latter evidence was stressed by the defendant on appeal, though it was not referred to in the defendant’s written submissions at the trial. The trial judge did not seek expressly to resolve that collision. Resolution of it would depend on satisfaction about the validity of Professor Morton’s approach. The trial judge dealt with attacks on Professor Morton’s evidence based on the unreliability of the plaintiff’s evidence. Independently of those attacks, however, there were difficulties with Professor Morton’s evidence, particularly in the light of the lay evidence about the stairs. The trial judge was not taken to any of these difficulties except for Professor Morton’s evidence about the extent to which the coefficient of friction depended on pressure. That is no doubt the explanation for why, in a case presenting innumerable other difficulties, he did not deal with the difficulties in Professor Morton’s evidence.

The hearing before this Court is a re-hearing: Supreme Court Act 1970 s 75A(5). Section 75A(6)(b) provides: “The Court shall have the powers and duties of the court … from whom the appeal is brought, including powers and duties concerning - … (b) the drawing of inferences and the making of findings of fact …” There are limitations on the exercise of those powers and the performance of those duties. One limitation relates to interference with credit-based findings; there is no issue about Professor Morton’s credibility in the sense of sincerity, and the trial judge’s findings are not based on it. Two other limitations relate to the taking of fresh points on appeal which might have been met by further evidence at the trial, and to matters which should have been put in cross-examination: the issue of whether Professor Morton’s evidence proves the plaintiff’s case is not in either category. Another limitation relates to points of which one party on appeal lacked notice: the plaintiff on appeal accepted that it was for this Court to read Professor Morton’s evidence and make up its own mind. Yet another limitation concerns discretionary judgments: but the acceptance or rejection of an expert’s opinion is not a discretionary matter.

In principle, even if none of these limitations apply, the plaintiff commenced the appeal with an advantage. The burden borne by a plaintiff at trial is not borne afresh from the start of an appeal against a verdict for that plaintiff. Here the plaintiff did not start the appeal with the onus of proving her case all over again. It is the defendant who bears the burden of persuading this Court that there was error and convincing it that its powers in relation to fact finding should be exercised, and its duties in relation to fact finding should be carried out, in its favour.

The conclusions in Professor Morton’s report ought not to be accepted uncritically. On examination it is difficult to be convinced by them. The lay history of incident-free use of the stairs suggests that they were not slippery. That inference from that history is preferable to Professor Morton’s conclusions. If the stairs were not slippery, the defendant was not in breach of its duty of care as occupier and employer. The appeal should be allowed on that ground.

There are two other aspects of Professor Morton’s report to be dealt with. First, the fact that there was, according to Professor Morton, non-compliance with Ordinance 70 does not of itself establish a breach of a duty of care. Secondly, the trial judge’s conclusion that there was probably grit on the stairs cannot establish a breach of a duty of care if that breach is not otherwise established, because the trial judge said it was impossible to quantify the extent to which the grit increased the slipperiness of the surface. In any event it is difficult to support a conclusion that grit was present in view of the plaintiff’s lie about it and Mr Firth’s denial that there was any grit. Remaining ground of appeal on liability: causation

In view of the conclusion reached in relation to Grounds 1-3, it is not necessary to consider the remainder of the Notice of Appeal or the Cross Appeal. However, in deference to the submissions advanced, the issues will be considered briefly.

Ground 5 of the Notice of Appeal was that the trial judge erred in finding that the injuries and disabilities which she complained of were caused by the fall. The trial judge accepted large parts, though not all, of the plaintiff’s evidence about her symptoms (at [207]). He accepted Dr Wilson’s diagnosis of fibromyalgia (at [208]-[211]) or in the alternative Dr Shand’s diagnosis of a psychiatric disorder (at [212]). He also accepted Dr Wilson’s opinion that there was a causal link between the fall and her condition (at [219]-[230]). Dr Wilson explained the medical basis of his diagnosis. In large measure there is concordance between various parts of the plaintiff’s evidence about her symptoms and experience, being evidence accepted by the trial judge, and the assumptions that underlay Dr Wilson’s evidence. The entire case excites suspicion, but Dr Wilson did give fairly clear evidence indicating the relationship between what can cause fibromyalgia and what he understood the plaintiff to be complaining of. The trial judge found that those complaints were in large measure genuine. Though other causes may have worsened the plaintiff’s condition, it is not possible for this Court in this case to reject the trial judge’s acceptance of Dr Wilson’s evidence. Other grounds of appeal

The balance of the grounds of appeal were supported by submissions that the plaintiff’s complaints were exaggerated, or in the alternative that only some of them were related to the fall. These contentions must fail for the reasons given in relation to Ground 5. Cross Appeal

The plaintiff cross-appealed on damages. In the end only two categories of matter were pressed.

The first was that the trial judge erred in finding that the plaintiff had a residual capacity to earn. The defendant demonstrated that at the trial in final address it had been conceded on the plaintiff’s behalf that the court might consider that she had some future earning capacity and that that equated to $200 net per week. The trial judge preferred that to a higher figure propounded by the defendant. The plaintiff’s complaint on this point is baseless.

The second matter, which was the subject of an application to amend the Notice of Cross Appeal, was that the trial judge failed to provide any amount for future pharmaceutical costs. These costs consisted of $19 per week for medication and two massage treatments at $50 per week. As to an allowance for medication, the defendant pointed out that the plaintiff itemised claims at the trial for “Future medical and rehabilitation expenses” totalling $76,860, including travel expenses of $6,121. The trial judge allowed the whole claim except for the travel expenses, which claim was not pressed. In later submissions, between the first and second sets of reasons for judgment, the plaintiff did not complain of, and indeed accepted, what the trial judge had done. Accordingly the claim now made for future pharmaceutical expenses should not be permitted because it goes beyond the case fought at the trial. As for the massage treatments, no claim for them was made below, and for that reason no claim should be permitted now. The application for leave to add the new ground of appeal is granted, but, if it became necessary to consider that ground of cross appeal, it ought to be rejected. Orders

The following orders are proposed. They follow from the reasons set out above. However, since the reasoning above in relation to Professor Morton’s report was in large measure not advanced by the appellant, it is not entitled to an order that the respondent pay the costs of the appeal. 1. The appeal is allowed. 2. The verdict and judgment for the respondent at trial are set aside. 3. The order of the trial judge that the appellant pay the respondent’s costs of the proceedings is set aside. 4. The Statement of Claim is dismissed. 5. The respondent is ordered to pay the appellant’s costs of the trial and of the appeal. 6. The respondent is to have a certificate under the Suitors Fund Act in relation to the costs of the appeal.