Fang v R

THE COURT: The appellant was found guilty by a jury of the stabbing murder of his friend, Mr Huang, which occurred on the night of 6 September 2014 or during the early hours of the morning of 7 September 2014. There was no dispute at the trial that the appellant fatally stabbed Mr Huang. However, the appellant raised the defences of mental illness and substantial impairment, as well as an issue in relation to intoxication.

On 21 November 2016, at the conclusion of the evidence and before closing addresses, Johnson J, on the application of the Crown, ruled that the defence of mental illness not be left to the jury: R v Fang (No 3) [2017] NSWSC 28. It is apparent from the guilty verdict that the jury rejected the defence of substantial impairment and were not persuaded that there was reasonable doubt arising on the basis of intoxication. His Honour sentenced the appellant to imprisonment for a term of 19 years, comprised of a non-parole period of 14 years with a balance of term of 5 years: R v Fang (No 4) [2017] NSWSC 323.

The sole question on the appeal was whether the trial judge erred in finding, at [110] of his judgment in Fang (No 3), that the appellant had not adduced evidence that he was suffering from a disease of the mind for the purpose of the common law defence of mental illness, and thus erred in refusing to leave the defence of mental illness to the jury.

The appellant did not take issue with his Honour’s statement of the law as to what constitutes mental illness, but submitted that there was sufficient evidence demonstrating that he had an underlying vulnerability to drug-induced psychosis for the defence of mental illness to go to the jury.

On the night of 6 September 2014, the appellant and Mr Huang were at the home of a friend, Mr Weng. The trial judge accepted, in his sentencing remarks, that during the course of the night, the appellant and Mr Huang consumed a number of bottles of beer between them and a substantial amount of the drug methylamphetamine (Ice). Blood taken from the body of Mr Huang at autopsy showed a very high, if not lethal, level of methylamphetamine in his system, although it was uncertain whether the delay in the post-mortem analysis had any effect on the concentration of the drug detected in Mr Huang’s system.

Mr Weng heard the appellant and Mr Huang arguing late on the evening of 6 September or in the early hours of 7 September, including hearing the appellant say to Mr Huang “Why did you threaten me?”. At some point after that, while still at Mr Weng’s house, the appellant stabbed Mr Huang to death. The trial judge, on sentence, accepted that the appellant believed that Mr Huang had said he wished to kill the appellant’s family.

It was the Crown case that after the stabbing, the appellant placed Mr Huang’s body into the boot of Mr Huang’s car, drove the car to a street near Rookwood Cemetery and left it there. The car and the body were not found until 21 September 2014. Gloves found in the vehicle bore the DNA of the appellant and Mr Huang.

Earlier, on 10 September 2014, the appellant, accompanied by his wife, Ms He, attended at his local church and informed the pastor, by using a throat-slitting gesture, what he had done. The pastor encouraged the appellant to go to the police. Before going to visit the pastor, the appellant had told his wife that he had “done something really bad”, again, using a throat-slitting gesture.

The appellant and his wife went to Campsie police station the following day, 11 September 2014, where the appellant informed the police that he had “killed someone” and that the person he had killed had given him “a lot of Ice”. The appellant said that he could not recall the name of the man that he had killed, but described him as owning a green sedan which had been taken to a place where there were “a lot of grave yards or cemetery”. The appellant told the police that the person he had killed had threatened to kill his family.

During the course of the interview, the police became concerned that the appellant was displaying signs of mental illness and arranged for him to be taken by ambulance to St George Hospital for assessment. Whilst at the hospital, drug and alcohol tests were carried out, which returned negative results. A psychiatric assessment was also undertaken. The appellant was assessed as not to be suffering from a mental illness or mental disorder and was discharged.

The medical evidence before the trial judge was that it was unsurprising that the appellant returned negative drug results when tested at the hospital on 11 September 2014, given that methylamphetamine has a short half-life and does not linger in the system. It was likely that there would be no trace of the substance in the body about 48 hours after ingestion. Assuming that the appellant had not ingested any more Ice between the time of the murder and the time of the testing, it would not be expected that he would have returned a positive drug result.

On 18 September 2014, the appellant travelled to China. He called his wife the following day from China, saying that his mother was very sick and that he had travelled to China out of concern for her health. The appellant returned to Sydney from China on 4 October 2014. He was charged with Mr Huang’s murder on 14 November 2016.

Before considering the trial judge’s reasons, it is necessary to refer to the evidence relating to the appellant’s drug use and his mental state before and after the stabbing.

The appellant did not give evidence at his trial. His wife gave evidence, as did Mr Weng. Expert psychiatric evidence was given by Dr Skinner, Dr Nielssen and Dr Allnutt. The psychiatrists all agreed that the appellant was suffering from a psychosis at the time he stabbed Mr Huang. The issue on the appeal was whether there was evidence sufficient to go to the jury that, at the time of the stabbing, the appellant suffered from a defect of reason arising from a disease of the mind.

The evidence of the psychiatrists is reviewed below in some detail, as it is the basis upon which the appellant contended that he had demonstrated that the defence of mental illness should have been left to the jury. It should be noted, however, that the history the appellant gave to each of the psychiatrists, including of the hallucinations he said he had experienced both before and after the stabbing incident, was the subject of a ruling pursuant to the Evidence Act 1995 (NSW), s 136.

Accordingly, the evidence of the history the appellant gave to the psychiatrists was evidence only of the fact of the history given and not evidence of the matters referred to in the history, subject to the following matters accepted by the Crown, namely, that there was evidence of drug use by the appellant in the period before the stabbing incident and that Mr Huang had made threats to the appellant, including that he was going to kill the appellant’s family. The Crown also acknowledged that there was a question whether the appellant had suffered from delusions before the night of the stabbing.

The appellant’s wife gave evidence that the appellant had been using cannabis and Ice for up to 12 months prior to when the stabbing occurred. She said that the appellant “hadn’t been normal for a period of time”. In cross-examination, she said that for at least most of 2014, he would “fly into a rage quite often and that scared us a bit”. Because of his behaviour, Ms He suggested to the appellant that he see a psychiatrist. However, there was no evidence that he did so.

Ms He did not give any evidence of the appellant hearing voices. In response to the direct question, “did he talk to you about hearing voices?”, she said that it was very hard to have a conversation with him as he would “often talk nonsense”. She gave no evidence of the appellant hearing voices. Ms He also said that when the appellant returned from China on 4 October 2014, he “appeared unhappy”.

The appellant gave a history to Dr Skinner that from July 2014, he had “occasional auditory hallucinations of voices on the radio”. As reported by Dr Skinner, the appellant said that the voices would tell him “that they had control of his fate and that someone would hurt him or kill his family members”. He told Dr Skinner that he “became very fearful but he did not tell anyone about it”. The appellant also gave Dr Skinner a history that during the first two or three months in prison, he experienced “occasional auditory hallucinations from the television”. These voices were speaking in Mandarin and told him that he and his family were at risk.

Dr Skinner explained the term “psychosis” in the following uncontroversial terms:

Dr Skinner said that it would probably take months of constant drug use for a psychotic state to develop. Dr Skinner was also asked about the effect of a psychotic state on an individual:

Dr Skinner considered that the appellant’s functioning was substantially impaired at the time of the stabbing. She was of the opinion that the appellant probably appreciated what he was doing when he carried out the act of stabbing Mr Huang, but that he did not appreciate that it was wrong, because he believed he was doing it to protect his family.

Dr Skinner then gave the following evidence:

The appellant relied upon this as evidence that, as he had in fact developed a psychosis, he fell into that category of person who was more susceptible or more vulnerable to doing so.

However, Dr Skinner’s evidence continued as follows:

The appellant also gave Dr Nielssen a history of voices coming “from the car radio or from the computer” and that he felt that his mind “was controlled”. He said that the voices persisted for three to five months after his reception into prison. The appellant also said that his wife had “conned” him into seeing the family doctor who had given him medication, but that he had stopped taking it as it made him feel very tired.

Dr Nielssen suggested a differential diagnosis of substance abuse disorder or substance induced psychosis, rather than a relapsing psychotic illness such as schizophrenia, because:

Dr Nielssen continued:

Dr Nielssen further stated:

Dr Nielssen was asked further questions about the “mental health aspect” of using Ice:

In cross-examination by the Crown, in a passage relied upon by the appellant, Dr Nielssen stated:

Dr Nielssen stated that the appellant’s use of Ice at the time of the murder “made his underlying condition worse”. Dr Nielssen reiterated his opinion as to the appellant’s vulnerability:

Dr Nielssen, in re-examination, confirmed his view that the appellant had an underlying condition. Significantly, for the resolution of the question in issue before the trial judge and on the appeal, Dr Nielssen identified the underlying condition as “an underlying vulnerability to psychosis”. He opined that an underlying vulnerability could be due to a number of factors, including a head injury, migration, or an unknown family history.

Dr Nielssen was dismissive of the St George Hospital psychiatric assessment that the appellant was not suffering from a mental illness or disorder on 11 September 2014, as it was not undertaken by a psychiatrist, was cursory, and was undertaken using a telephone interpreter and in circumstances where no corroborative information was gathered. Dr Nielssen also observed that the appellant was not assessed by a psychiatrist in the year after his reception into prison.

It should be noted at this point that Dr Nielssen’s opinion that the appellant’s psychotic illness was an underlying condition that was present before he stabbed Mr Huang was based upon an understanding that the appellant had been prescribed anti-psychotic medication by his general practitioner and that he suffered hallucinations for some months after the offence. Neither of these matters was established in the evidence, as discussed later in these reasons. Indeed, there was no record of the appellant attending upon his general practitioner in the months before the stabbing incident, nor having been prescribed any anti-psychotic medication.

Dr Allnutt examined the appellant in September 2015, at which time he did not manifest symptoms of a psychotic disorder. The appellant gave Dr Allnutt a history suggesting that he had suffered a head injury when he fell off a car at the age of 16 or 17, which put him in a coma. However, Dr Allnutt stated that there was “no clear evidence of any neurological problem” at the time that he examined the appellant. In his consultation with Dr Allnutt, the appellant did not describe a family history of mental illness, such that Dr Allnutt considered that the appellant did not manifest a strong genetic predisposition to mental illness. Dr Allnutt considered that the appellant did not have a personality disorder and, in particular, did not have an antisocial personality disorder.

Dr Allnutt referred to the appellant’s history of family stressors in the three to four years before the stabbing incident, namely, that the appellant’s mother was involved in a serious motor vehicle accident, both his parents were diagnosed with cancer and the appellant’s wife miscarried with twins. In Dr Allnutt’s opinion, this triggered the onset of a depressive episode. The appellant’s history was that it was in this context that he was introduced to Ice. At that time, he was already drinking alcohol and using cannabis intermittently.

Dr Allnutt was of the opinion that, on the information available, “drugs triggered the onset of a psychosis and as a consequence [the appellant] had a drug-induced psychosis”.

Dr Allnutt then gave the following evidence:

Dr Allnutt agreed in cross-examination that the psychosis from which the appellant was suffering at the time of the murder was temporary and had resolved by September 2015.

The trial judge stated, at [5], that the matter upon which he was ruling was the question:

His Honour observed, at [10], that following his arrest, the appellant was not diagnosed with any psychiatric illness. His Honour further observed that by the time the appellant was examined by the three psychiatrists in 2015 and 2016, he did not appear to be suffering from any psychiatric illness.

His Honour noted, at [31], that upon the assumptions arising from the evidence and the history given by the appellant, each of the psychiatrists was of the opinion that, at the time of the stabbing, the appellant:

His Honour further observed, at [32], that although the appellant could have experienced a drug-induced psychosis arising from his regular use of Ice, each of the psychiatrists had accepted the critical importance of the “final ingestion” of Ice before the stabbing to the appellant’s mental state at the time of the stabbing.

The trial judge, after referring to the factual background, reviewed the evidence as to the appellant’s use of Ice and examined the psychiatric evidence concerning the appellant’s mental state at the time of the stabbing. Having done so, his Honour noted, at [36], that the appellant had no personal history of mental illness, nor was there any family history of mental illness. His Honour noted that since being taken into custody on 4 October 2014, there had been no diagnosis of mental illness, including psychosis, nor had he been treated for any psychiatric condition.

His Honour referred, at [40], to Dr Allnutt’s evidence that although the use of Ice may cause actual changes in the brain, “there was no evidence in the trial that [the appellant] had experienced any such changes”. His Honour then observed, at [41], that:

His Honour noted, at [45], the Crown’s reliance on the appellant’s “purposeful conduct” in allegedly wrapping Mr Huang’s body in the doona, placing the body in Mr Huang’s car, driving approximately 12 km, and then leaving the car, and the body, at Lidcombe. His Honour considered that this conduct would have been a “significant” issue for the jury, if the defence of mental illness had been left to the jury. However, the question for his Honour’s determination was whether to leave the defence to the jury. His Honour stated, at [46], that he had approached that question on the basis that the defence ought to be left to the jury if there was some evidence to support it such that the defence was fairly open: see R v Ayoub [1984] 2 NSWLR 511 at 515. The question therefore, as his Honour posed it at [47], was “whether there was evidence of a defect of reason due to a disease of the mind, so that the defence of mental illness should be left to the jury”.

His Honour observed, at [62], that what constitutes mental illness is a question of law. His Honour stated, relevantly for this matter, at [68]ff, that the following propositions emerge from the authorities concerning the defence of mental illness.

First, an accused person is presumed to be sane and possessed of a sufficient degree of reason to know the nature and quality of his or her act, and that what he or she is doing is wrong until he or she proves to the contrary: see R v M’Naghten (1843) 8 ER Rep 718; R v Porter (1933) 55 CLR 182; [1933] HCA 1 at 183-184; R v S [1979] 2 NSWLR 1 at 61; Howard and Westmore, Crime and Mental Health Law in New South Wales (2nd ed, 2010, LexisNexis) at 274-275.

Secondly, the onus lies upon an accused person to establish the defence of mental illness on the balance of probabilities: Porter at 184; S at 41; Howard and Westmore at 272-274.

Thirdly, his Honour stated:

His Honour then conducted an extensive review of the authorities regarding the M’Naghten rules and intoxication. His Honour noted, at [85], that in R v Falconer (1990) 171 CLR 30; [1990] HCA 49, which adopted and applied the judgment of King CJ in Radford v R (1985) 42 SASR 266, it was held that the defence of mental illness was not available “where an accused person’s condition is the product of self-induced intoxication by alcohol or drugs”. His Honour also observed, at [94], that the case law in New South Wales supported the proposition that:

His Honour considered, at [96] and [102], that the Victorian case law supported the proposition upon which the Crown relied, that is, that a drug-induced psychosis alone does not constitute a disease of the mind: see especially R v Martin (No 1) (2005) 159 A Crim R 314; [2005] VSC 518; R v Sebalj [2006] VSCA 106; R v Konidaris [2014] VSC 89; R v Gibson [2016] VSC 634. His Honour considered, at [104], that Canadian authority also supported the Crown’s argument: see Bouchard-Lebrun v R [2011] 3 SCR 575; [2011] SCC 58.

His Honour then considered, at [105]-[112], the application to this case of the principles he had derived from the case law. His Honour observed, at [106], that Ice was a “contemporary scourge in the community” but that individuals, such as the appellant, “make a choice” as to whether to use it and that such individuals may be taken to have some awareness of its severe effects.

His Honour referred, at [107]-[108], to the policy lying behind the defence of mental illness and noted the “narrow parameters” within which the defence operates. As his Honour observed, at [108]:

His Honour concluded, at [109], that this was not a case where there was evidence that the appellant had an underlying existing mental illness which was triggered or exacerbated by his use of Ice. For that reason, the case was to be distinguished from those New South Wales and Victorian decisions where the accused had a pre-existing mental illness. Rather, in his Honour’s view, stated at [110], the evidence indicated that any drug-induced psychosis from which the appellant was suffering at the time of the stabbing was the product of his use of Ice and that the appellant did not otherwise suffer from a disease of the mind.

In coming to this conclusion, his Honour noted that the appellant recovered spontaneously from his psychosis when he ceased using Ice. His Honour concluded, at [110], that the psychosis was “a temporary and not persisting state which flowed solely from [the appellant’s] use of prohibited drugs”. In his Honour’s view, the appellant had not “adduced evidence that he was suffering from a ‘disease of the mind’ for the purpose of the common law test of mental illness”.

This appeal raises the application of two interrelated principles: first, the principles governing the defence of mental illness; and secondly, what must be established in order for the defence to be left to the jury. In determining whether the defence should have been left to the jury, it is important to understand at the outset that, as the trial judge noted, what is necessary for the defence of mental illness to be established is a question of law: see Falconer at 49 (per Mason CJ, Brennan and McHugh JJ), 60 (per Deane and Dawson JJ), and 74 (per Toohey J). As Gaudron J explained in Falconer at 84, it is a “question of law whether [the] evidence raised a mental state involving a disease of the mind or natural mental infirmity”. Whether or not the accused suffered from a mental illness at the relevant time is a question of fact: see Falconer at 60 (per Deane and Dawson JJ) and 74 (per Toohey J).

It is convenient to refer to the second of these principles first. Where an accused raises a defence of mental illness, there may be, as was the case here, a question whether that defence should be left to the jury. In R v Shields [1967] VR 706, the Supreme Court of Victoria stated, at 707-708, that “if the evidence at a trial reasonably raises a defence of insanity it is the duty of the trial judge … to submit that issue to the jury”. The test was stated in similar terms in respect of sane automatism in Woodbridge v R (2010) 208 A Crim R 503; [2010] NSWCCA 185. In that case, Davies J (McClellan CJ at CL and R S Hulme J agreeing in part) stated, at [73]:

In R v Youssef (1990) 50 A Crim R 1, Hunt J stated, at 3, that “[t]he authorities make it clear that such a reasonable possibility must be shown by admissible evidence”.

The trial judge approached the question of whether to leave the defence of mental illness to the jury on the basis that the defence ought to be left if there was some evidence to support it such that the defence was fairly open, as stated by Street CJ (Slattery J agreeing) in Ayoub at 515. Both parties accepted that this was the applicable test.

We do not consider there to be any material difference between this formulation of the question and that stated in the more recent decision of Woodbridge. No submissions were made by the parties as to any difference between the tests in Ayoub and Woodbridge.

The defence of mental illness in New South Wales is governed by the Mental Health (Forensic Provisions) Act 1990 (NSW), s 38. That section provides as follows:

A “mentally ill person” is defined in s 3 to have the same meaning as in the Mental Health Act 2007 (NSW). “Mental illness” is also defined in that Act. It is not necessary to dwell on those definitions for present purposes, as it is accepted, as the trial judge pointed out at [67], that s 38 operates to give effect to the common law principles concerning the defence of mental illness. In essence, these principles involve the application of the M’Naghten rules, as those rules have been explained and applied in this jurisdiction.

In M’Naghten, the House of Lords stated:

The meaning of the expression “disease of the mind” within the M’Naghten rules was considered by King CJ in Radford, at 274:

In Radford, King CJ also stated that for there to be a disease of the mind, there had to be “an underlying pathological infirmity of the mind”. However, his Honour considered that the underlying infirmity did not have to be permanent and could be of long or short duration. As his Honour explained, at 274-275:

In Falconer at 54, Mason CJ, Brennan and McHugh JJ considered that the dichotomy drawn by King CJ between mental illness and a healthy mind affected by an external stimulus was correct, but added:

Their Honours then considered the difficulties that arise when a temporary mental disorder or disturbance is precipitated by psychological trauma. Their Honours noted, at 55, that, in a case of “a transient malfunction of the mind precipitated by psychological trauma”, the problem lies in determining the cause of the malfunction, that is, whether it is the trauma itself or “the natural susceptibility of the mind to affection by psychological trauma”. In determining the relevant cause, their Honours considered that it was necessary for the law to postulate:

Their Honours continued that if a psychological trauma causes:

Toohey J (Deane and Dawson JJ agreeing) also endorsed as correct the approach of King CJ in Radford in the passages cited above. His Honour additionally cited with approval the following passage from Radford:

As these judgments indicate, a difficult question can arise where a temporary mental disorder or disturbance is produced by external factors. Gaudron J also made reference to this in Falconer, at 84-85, as follows:

There are a number of decisions of intermediate appellate courts which have applied the principles discussed in Radford and Falconer. By reference to Falconer, in R v De Souza (1997) 41 NSWLR 656, Powell JA (Studdert and Levine JJ agreeing), stated the matter succinctly in terms that when dealing with questions of criminal responsibility, “disease” excludes effects:

In Derbin, the accused was suffering from the mental illness of schizophrenia whilst also being affected by alcohol and drugs at the time of the commission of the offence. The Court did not refer to Radford or Falconer. Rather, Mason P quoted, at [70], from R v Stones (1955) 56 SR(NSW) 25, in which the Court stated that:

As the trial judge in this case pointed out at [87], there may be some tension between this statement and the High Court’s decision in Falconer and its adoption of the statements in Radford, as discussed above. This Court is of course bound by Falconer and, in any event, the accused in Derbin had a pre-existing mental illness of schizophrenia, so that that case is distinguishable on its facts. Further, as the trial judge also commented, Mason P’s observations in Derbin seemed to accept “the need for an underlying psychiatric condition apart from drug or alcohol use” for the defence of mental illness to be available.

We have not found it necessary to review all of the authorities to which the trial judge referred, including the Victorian and Canadian decisions. As his Honour correctly stated, those authorities support the proposition that “a drug-induced psychosis (unaccompanied by a separate psychiatric illness) does not constitute a disease of the mind as understood in the common law”. However, as the appellant placed particular reliance on the observations made in Doolan and R v Pahl [2017] ACTSC 68, it is necessary to consider those decisions.

Doolan concerned the question whether the accused, who had murdered her infant son, had made out the defence of mental illness. Hall J referred, at [112]ff, to the principles of the defence of mental illness, citing the statement of King CJ in Radford set out above at [71], and the observations of Gaudron J in Falconer, set out above at [72]. A particular focus of the appellant’s reliance on Doolan was the psychiatric evidence of Dr Westmore in that case, who was recorded in the judgment as having said that:

The appellant then referred to the following passages of Hall J’s judgment:

As explained below, the appellant’s reliance on Doolan revolved around what he contended was an acceptance both legally and medically that a vulnerability to psychosis as a result of the ingestion of drugs is evidence of a mental illness for the purposes of the defence, such that the defence should have been left to the jury.

The appellant also relied upon the decision of the Supreme Court of the ACT in Pahl. In that case, Murrell CJ was concerned with the defence of mental impairment for the purposes of the Criminal Code (ACT). Mental impairment is defined in s 27 of that Act to include mental illness. “Mental illness” is defined, relevantly, in the following terms:

The Criminal Code (ACT), s 28 states the test for mental impairment and criminal responsibility, relevantly, as follows:

Paragraphs (a) and (b) of the definition accord with the M’Naghten definition. Paragraph (c) adds a further descriptor of what constitutes mental impairment for the purposes of criminal responsibility in the ACT legislation.

Murrell CJ observed, at [117], that the distinction drawn in Radford and Falconer between the effect of external factors on a healthy mind and circumstances where the person was suffering from an underlying mental abnormality, “sits uncomfortably with contemporary understanding of mental functioning”. Her Honour explained:

Her Honour, at [118], referred to the effects of alcohol and other intoxicating substances, stating that:

Her Honour then posed the question required by the definition of “mental illness” in the legislation, namely whether “such an underlying pathological infirmity of the mind give[s] rise to a defence of mental impairment”.

Her Honour, after reviewing the authorities, including the primary judge’s decision in Fang (No 3), which is the subject of this appeal, concluded, at [133]:

It will be apparent from the emphasised portion of para (b) above that the appellant sought to gain support for his argument that the defence of mental illness should have been left to the jury from Murrell CJ’s acknowledgement that persons may be “vulnerable to external stimuli”.

As mentioned earlier, the appellant did not dispute that the trial judge had correctly stated the law, but rather that his Honour erred in finding that there was no evidence to go to the jury on the question whether he was suffering from a mental illness when he stabbed the deceased. That question must be determined by reference to the legal test for mental illness and the test as to the sufficiency of evidence required for the defence of mental illness to be left to the jury.

The legal test for whether a person suffered from a mental illness at the time of the commission of a crime is that stated by Falconer, adopting the passages from Radford discussed above at [66]-[71]. In essence, it must be established that there is a defect of reason in the M’Naghten sense which results from “an underlying pathological infirmity of the mind”: see Radford at 274; Falconer at 53.

The difficulty which has arisen in the cases, and which was recognised in both Radford and Falconer, is where a person suffers from a temporary disorder of the mind associated with the ingestion of intoxicating substances. In those cases, the question is whether the person suffered from a mental illness in the legal sense or whether the person was acting under an external stimulus such as drugs or alcohol but was otherwise of sound mind.

In both Radford at 274 and Falconer at 54, there is an acceptance that there will be a mental illness in the legal sense where the mental disorder is “prone to recur”. It is in that context that King CJ in Radford, as endorsed by the High Court, referred to “external factors” operating on an “otherwise healthy mind”. In part, it was this aspect of the concept of mental illness with which Murrell CJ was dealing in Pahl in the passages set out above. Her Honour stated, by reference to the qualifying provision in the Criminal Code (ACT), s 27(3), that a tendency to recurrence may be evidence of a mental illness. Her Honour was of the view, however, that a tendency to recurrence does not necessarily establish that the person has a mental illness. To that extent, her Honour’s view departs from the statements in Radford and Falconer which we have already discussed. In those cases, it was stated that a proneness to recurrence meant that there was a mental illness, whereas on her Honour’s view, a proneness to recurrence was an evidentiary matter in determining whether there was a mental illness.

As to the balance of her Honour’s reasons and contrary to the appellant’s submissions, there is nothing in her observations that is of assistance to the appellant, including her reference, at [117], to current understandings of “mental functioning” sitting uncomfortably with the distinction drawn in Radford and Falconer between an external stimulus on a healthy mind and an underlying mental illness. Significantly for the appellant’s argument, at no stage did her Honour elevate vulnerability to psychosis in a person who has ingested drugs or alcohol, to a mental illness.

The same may be said of the observations of Hall J in Doolan. In Doolan, there was evidence that the accused had suffered a number of episodes of drug-induced psychoses prior to the occasion on which she killed her son, which gave rise to a vulnerability to further psychosis. The trial judge was satisfied that quite apart from the effect of the drugs she had taken on the night and “whether they would have affected her capacity to reason”, the accused had an underlying condition that meant that “she could not reason with a moderate degree of composure”. His Honour was satisfied therefore that the defence of mental illness was available to the accused. His Honour did not find that the appellant’s vulnerability to “further psychosis” as a result of the drugs she took was a ‘mental illness’, as the appellant in this case contended.

It may be that, at some point, the observations in Radford and Falconer as to the tendency of a mental disorder, present at the time of the offending, to recur will have to be considered having regard to the “contemporary understanding of mental functioning”. However, that could only be on the basis of expert evidence. Significantly in this case, there was no evidence of any such tendency or of any recurrence, as discussed later in these reasons.

There was no dispute on the medical evidence that the appellant was suffering from a drug-induced psychosis at the time that he stabbed Mr Huang and that he probably did not appreciate that what he was doing was wrong. However, the authorities are clear that that is not sufficient to demonstrate that a person is suffering from a mental illness for the purposes of the common law defence. This leads to the question of what mental illness the appellant was suffering, if any.

The appellant contended, relying on the evidence of Dr Nielssen in particular, that there was evidence that he had an “underlying vulnerability to psychosis” such that the defence of mental illness should have been left to the jury. However, on questioning from the bench, the appellant accepted that he was not able to specifically identify the underlying mental illness from which he was suffering and conceded that neither could the psychiatric experts. Nonetheless, he contended that the expert evidence identified that he had an “underlying susceptibility, vulnerability to develop a psychosis if there was one triggered by an external stimuli” and that that was sufficient for the defence of mental illness to be left to the jury.

The expert evidence was consistent in that it accepted that some people are more vulnerable to developing a dependence upon drugs and to the occurrence of psychosis with the long term use of drugs. “Long term” for this purpose was accepted to be “months”. Dr Nielssen, upon whose evidence the appellant placed particular emphasis, considered that the appellant had “an underlying condition”, which he described as “an underlying vulnerability to develop psychotic illness”. Dr Allnutt gave evidence that there was early evidence-based research indicating that the long-term ingestion of methamphetamines caused brain damage. In Dr Allnutt’s opinion, if symptoms of psychosis “persist longer than a month then that is consistent with an independent, almost illness process happening”.

The appellant thus placed emphasis on the fact that the psychiatrists had given evidence that different people have different susceptibilities to drugs and other intoxicating substances. In this regard, the appellant submitted that the decisions in Doolan and Pahl were directly on point and supported his case that an underlying vulnerability to psychosis constituted, or could constitute, a mental illness for the purposes of the defence of mental illness. For the reasons stated above, we do not accept that submission.

As already indicated, the question for the trial judge was whether there was some evidence from which it could be inferred that there was a reasonable possibility that the appellant was mentally ill, having regard to the meaning of that term for the purposes of the defence of mental illness. That question was essentially an evidentiary one. In this regard, it was necessary for the trial judge to ascertain whether there was evidence to support the views expressed and opinions given by the psychiatrists. It was also necessary to understand whether, given the medical evidence, the appellant was suffering from a mental illness in a legal sense.

One of the significant factors to which each of the psychiatrists referred in considering whether the appellant was suffering from a mental illness was the history he gave them of having suffered from auditory hallucinations before and after the stabbing incident. The psychiatrists considered the continuation or recurrence of aspects of a disordered mental state in the form of continuing hallucinations to be relevant to the question whether the appellant was suffering from a mental illness at the time of the stabbing incident. Had there been some evidence of this kind, the appellant would have had a basis upon which to argue that the defence of mental illness ought to have been left to the jury.

The appellant also gave a history of having been prescribed anti-psychotic medication in the months prior to the murder. This aspect of the expert evidence was, as we have indicated, subject to a ruling under the Evidence Act, s 136.

The difficulty for the appellant, therefore, was that there was no evidence that he was experiencing auditory hallucinations either in the period before or after the stabbing. His wife did not give such evidence. Nor was there anything in the appellant’s Justice Health records to indicate that he had reported experiencing auditory hallucinations, or that he had been observed to exhibit unusual behaviour, which might be taken as an indication of ongoing mental health problems. The records of the appellant’s general practitioner, which were in evidence, did not record that he had been prescribed anti-psychotic medication during this period, and there was no evidence that he had been to see a psychiatrist.

The appellant did not give evidence and there was no objective evidence, such as might have been revealed on an MRI, of changes to the brain that may have indicated the presence of a mental illness. At its highest, the evidence was that the appellant had exhibited behavioural changes, including a tendency to fly into a rage, in the months before the murder. However, his wife’s evidence in this regard was quite general, as was her evidence that the appellant would speak “nonsense”. Ms He did not, and was not asked to, elaborate on what she meant by this. In our opinion, her evidence did not give rise to an available inference that the “nonsense” to which she referred was the appellant responding or otherwise talking to hallucinatory voices. It could have been, for example, because he had just taken drugs. This, of course, is a matter of speculation only. The point is there was no evidence that he had suffered hallucinations in the months before the stabbing.

None of the psychiatrists commented on Ms He’s evidence as to the appellant’s conduct in the period leading up to the stabbing. To the extent that the medical experts focussed on the appellant having had hallucinations in the periods before and after the stabbing, their views were based on an unproven history. Nor was there a history of mental illness, either personally or in his family.

As we have explained, given the s 136 limitation on the evidence of the psychiatrists, and the limited extent of the evidence given by the appellant’s wife, there was no evidence such that the defence of mental illness was fairly open: see Ayoub at 515; and no evidence from which it could be inferred that there was the reasonable possibility that the appellant was mentally ill for the purposes of the defence: see, by analogy, Woodbridge at [73]. The suggestions in the psychiatric evidence that some persons who ingest drugs over a period of time may be vulnerable to developing a psychosis was not sufficient either as a matter of diagnosis to establish a disease of the mind, or of the appellant suffering such a disease of the mind at the time he stabbed Mr Huang.

The appeal should be dismissed.

The Court makes the following orders: