In the matter of Mayne Pharma Group Limited

1. [1]

   These proceedings were commenced by Mayne Pharma Group Ltd (Mayne) on 18 February 2026. There are four defendants. The first defendant, Cosette Pharmaceuticals (Cosette), and the second defendant, Cosette Pharmaceutical Holdings (Cosette Holdings) (together the Cosette parties), have appeared. The third and fourth defendant have not appeared to date in this proceeding. They have addresses outside Australia. The time for them to enter an appearance, assuming they have been served, has not yet expired. They may appear.

2. [2]

   There have been other proceedings between Mayne and Cosette in this court. Cosette Holdings was not a party to those other proceedings. Nor were the third or fourth defendant. A substantive judgment in those proceedings was delivered by Black J on 15 October 2025: In the matter of Mayne Pharma Group Limited [2025] NSWSC 1204. I will refer to those proceedings as the MAC proceedings, and to the judgment as the MAC judgment. Mayne, who was the plaintiff, was successful in those proceedings. Cosette has appealed against the orders made in the MAC judgment. I will call that the MAC appeal. The MAC appeal is listed for hearing on 2 and 3 June 2026.

3. [3]

   By way of very crude summary, the MAC proceedings concerned a scheme implementation deed (SID) dated 20 February 2025, by which a subsidiary of Cosette was to acquire all of the ordinary shares of Mayne. The MAC proceedings concerned claims about whether or not the SID had been validly terminated or was void ab inititio. One of the central issues was whether there had been a material adverse change, or “MAC”.

4. [4]

   The MAC proceedings were heard in circumstances of urgency. The circumstances were explained by Black J in the MAC judgment as follows (at [5]):

5. [5]

   In the current proceedings, Mayne sues the defendants for losses associated with alleged breaches of the SID. An aspect of its case in these proceedings, which was not before Black J, is whether the FIRB decision by the Treasurer was, in effect, procured by Cosette and others based on a communication with the Treasurer by Cosette that was knowingly false or was misleading or deceptive. Mayne brings the proceedings on its own behalf and on behalf of its shareholders. It contends that it holds Cosette’s obligations under the SID on trust for its shareholders.

6. [6]

   The Cosette parties apply for an interim stay of this proceeding until the determination of the MAC appeal, with any proposed extension of that stay to be addressed at that time.

7. [7]

   In the current proceedings, Mayne filed and served its points of claim on 5 March 2026. At a directions hearing of this proceeding on 17 March 2026 before Black J, the Cosette parties were directed to file their defences by 15 April 2026. Given that looming deadline, it is necessary for me to resolve the Cosette parties’ application for a stay promptly.

8. [8]

   The Cosette parties seek the interim stay on two grounds which, they submit, are essentially ones of case management directed towards the statutory mandate under s 56 of the Civil Procedure Act 2005 (NSW). First, they contend that judgment in the MAC appeal will, at the very least, significantly narrow the complex issues the Court is asked to determine in this proceeding. They contend that the outcome of the appeal may render this proceeding pointless. As part of this ground, they contend that, given that there is no longer any urgency, and also given that Mayne has not established any liability or any entitlement to damages in the earlier proceeding, it does not further the interests of justice for the Court and the parties to expend resources progressing substantial and complex issues in this proceeding that may become redundant. Secondly, they contend that staying this proceeding until judgment in the MAC appeal will avoid or significantly reduce the risk of inconsistent findings arising from the parallel progression of the MAC appeal and this proceeding.

9. [9]

   The Cosette parties submitted that their short point is that the relationship between the MAC proceeding, the MAC appeal and this proceeding is unique; that given the substantial overlap between the allegations made in the MAC proceeding with those made in this proceeding, and the centrality to this proceeding of findings, declarations and orders now under appeal, an interim stay is appropriate.

10. [10]

    For the following reasons, I am not going to make an order that there is an interim stay of the proceedings.

Principles

1. [11]

   I can briefly identify the relevant principles. There was no real dispute about them.

2. [12]

   The power to order a stay of proceedings arises under s 67 of the Civil Procedure Act 2005 (NSW) and the Court’s inherent power to prevent injustice.

3. [13]

   A proper starting point in considering whether to exercise the power to grant an interim stay is the fundamental principle that a plaintiff is entitled to have his or her action tried in the ordinary course of the procedure and business of the Court, subject only to an exercise of judicial discretion on proper grounds: see Rochfort v John Fairfax & Sons Ltd [1972] 1 NSWLR 16 at 19. It has also been stated that it is a grave matter to interfere with this entitlement by a stay of proceedings which requires justification on proper grounds: see McMahon v Gould (1982) 7 ACLR 202; 1 ACLC 98 at 206.

4. [14]

   In Wigmans v AMP Ltd (2019) 103 NSWLR 543; [2019] NSWCA 243, Bell P (with whom Macfarlan, Meagher, Payne and White JJA agreed) observed (at [95]) that the exercise of a discretion to stay proceedings involves an assessment as to whether the ends of justice require such a remedy. His Honour expressed the view that this is a larger task than one of mere “case management”.

5. [15]

   The parties agreed that I should approach the question before me by assessing whether the ends of justice require an interim stay. That is what I have done.

6. [16]

   Mayne also relies on the often-stated proposition that a successful litigant, except in special or exceptional circumstances, is "entitled to the fruits of its judgment": see, for example, Alexander v Cambridge Credit Corporation Ltd (Receivers Appointed) (1985) 2 NSWLR 685; 10 ACLR 42 at 693. That proposition is most often invoked in the context of an application to stay the execution of a judgment under appeal. That is not what is happening in this case. The stay that is sought here is a stay of separate proceedings.

7. [17]

   However, it is true that in the current proceedings, Mayne is seeking to reap the benefit of issue estoppels that it says arise from the MAC judgment. To that extent, it is seeking, legitimately, to take advantage of its victory in the MAC proceedings and it is entitled to do that, notwithstanding that there is an appeal on foot. This reinforces the proposition that the proceedings should proceed in the ordinary course of the procedure and business of the Court, unless the ends of justice require that there be a stay.

Impact of the appeal on the current proceedings

1. [18]

   I turn to the Cosette parties’ first ground, which concerns the potential impact of the MAC appeal on the current proceedings.

2. [19]

   The Cosette parties’ submission that judgment in the MAC appeal will, at the very least, significantly narrow the complex issues the Court is asked to determine in this proceeding overstates matters. If Cosette is unsuccessful in their appeal, then (subject to an application for special leave to appeal to the High Court) the issues that the Court is required to determine in this proceeding will remain unchanged. I accept that the decision of the Court of Appeal could make certain (again subject to any application for special leave) issue estoppels that are presently contingent on the outcome of the appeal. But the complexion of the proceedings will remain essentially the same.

3. [20]

   If Cosette succeeds in its appeal, the issues in this Court may be narrowed. They may be narrowed to the point that the current proceedings become unviable. They may be narrowed to a lesser extent. There are various possibilities depending on the character of any success of Cosette in the appeal. I do not need to descend into those complexities. It is sufficient for me to note that there is a real prospect that if these proceedings are not stayed and Cosette succeeds on appeal, there will be a lot of work done and expenses incurred in these proceedings that will be redundant. This is a matter that the Cosette parties point to in favour of a stay.

4. [21]

   If, following a loss in the Court of Appeal, Mayne cannot maintain these proceedings, in whole or in part, Mayne is at serious risk of an adverse costs order in respect of costs thrown away by the defendants. Any decision on costs will be determined on its merits, but the ability to make an application for costs is a mechanism that can, at least to some extent, ameliorate any prejudice to the Cosette parties in the form of wasted costs. I recognise that an order for costs rarely fully compensates for wasted costs, and will not make up for time wasted by company executives in the work they might be required to do, including things such as preparing affidavits. I accept that the prospect of a costs order provides a mechanism by which the Cosette parties could obtain significant, but not complete, compensation if there is redundancy.

5. [22]

   The Cosette parties also submit that if the proceedings continue, there is also a risk that scarce judicial resources will be utilised in a way that will turn out to be wasted.

6. [23]

   Against these matters, Mayne contends that delay in these proceedings risks an "irreparable element of unfair prejudice": see Aon Risk Services Australia Ltd v Australian National University (2009) 239 CLR 175; [2009] HCA 27 at [5] (per French CJ). Mayne relied, in particular, on the following remarks of Heydon J (at [137]):

7. [24]

   It is not merely the commercial interests of Mayne or the Cosette parties that are in play. These proceedings concern the commercial interests of Mayne’s shareholders, on whose behalf Mayne seeks remedies as trustee.

8. [25]

   In weighing these considerations, it seems to me that the balance falls decisively against a stay. The prejudice to the Cosette parties if the proceedings are not stayed, and if Cosette succeeds on the appeal, may be substantially cured by an order for costs. There is no suggestion that Mayne would not be good for any costs. That prejudice does not require the remedy of a stay in circumstances where a stay will hold up Mayne’s right to have its case heard and determined as efficiently as the Court processes will allow. Mayne has a right to prosecute its case, including by seeking to take advantage of the finding made in the MAC proceedings. It is prejudiced by delay that cannot properly be measured or remedied. Delay diminishes public confidence in the due administration of justice.

9. [26]

   I do not consider that the possibility that judicial resources will also prove to be wasted if the Court of Appeal allows the appeal tips the balance. It is the Court’s duty to hear and determine matters that come before it. It is often the case that judicial resources will be expended in circumstances where the resources might be seen to have been wasted. It happens, for example, when a case settles shortly before trial, or even after a trial but before judgment. I do not think the Court should shirk from undertaking work associated with the management of the proceedings against the possibility that a successful outcome in the MAC appeal might mean that some of that work will turn out to have been unnecessary.

10. [27]

    I also note that the Cosette parties submitted that they are in an invidious position in preparing their defences responsibly in circumstances where the MAC judgment stands and, unless set aside, may or will give rise to issue estoppels. If the MAC judgment makes it more difficult to plead a defence, and that the drafting requires unusual nuance, and I am not convinced it does, that seems to me to be an incidental feature of complex commercial litigation. It does not support a stay.

A risk of inconsistent findings

1. [28]

   I also reject the contention that staying this proceeding until judgment in the MAC appeal will avoid or significantly reduce the risk of inconsistent findings arising from the parallel progression of the MAC appeal and this proceeding.

2. [29]

   The prospect of inconsistent findings exists if these proceedings are heard and determined before judgment in the MAC appeal. That prospect is exceedingly remote.

3. [30]

   The MAC appeal, as I have noted, is listed for a two-day hearing on 2 and 3 June 2026. It is reasonable to anticipate a decision on the appeal before the end of August this year, if not much sooner than that. No doubt that the Court of Appeal could be informed, if necessary, of the status of this proceeding and the difficulties that could be occasioned if judgment is delayed.

4. [31]

   It is too early to say when the current proceedings will be ready for hearing. There is no risk that the extreme expedition given to the MAC proceedings will be given to the hearing of this proceeding. That is for the simple reason that the exceptional circumstances of the MAC proceedings no longer exist. The current proceedings are essentially about damages; they are not proceedings seeking declarations in respect of a transaction that, if live, had an end date of 20 November 2025.

5. [32]

   Having regard to the complexity of the matter, it seems highly unlikely that it will be ready for hearing before the end of August this year. It is almost inconceivable that a hearing would occur before the final quarter of this year. As things stand, a hearing in late 2026 or the first part of 2027 is not an unreasonable expectation. That is almost certain to be long after the Court of Appeal has delivered judgment in the MAC appeal.

6. [33]

   The remote prospect of inconsistent findings can be managed, and is best managed, if the remote prospect becomes a real one.

Strength of the case

1. [34]

   Mayne submitted that I should take into account that Cosette’s prospects on the MAC appeal are weak. It accepted that the appeal was reasonably arguable but submitted that Cosette’s prospects were poor.

2. [35]

   I accept that as, a matter of principle, I could take into account a broad brush view formed about the prospects of the appeal: see, for example, Cassegrain v Cassegrain [2015] NSWCA 387 at [21].

3. [36]

   However, it is apparent that the MAC proceedings were complex and the appeal raises matters of real complexity. Trying to form a broad brush view about prospects in those circumstances is fraught. It is not an exercise I need to undertake in order to exercise my discretion and I decline to do so.

Delay

1. [37]

   Mayne also relied on what it called the delay in prosecuting the appeal.

2. [38]

   I accept that a factor that also weighs against a stay is that the predicament now faced by the Cosette parties is, in part, a product of Cosette’s own making.

3. [39]

   Cosette did not take up the opportunity, afforded by Black J, to seek an expedited appeal: see [5] of his Honour’s reasons as set out at [4] above. The Cosette parties contend that the urgency vanished with the Treasurer’s FIRB decision. It may be accepted that the urgency was altered by the Treasurer’s preliminary indication given on 30 October 2025.

4. [40]

   Cosette filed a notice of intention to appeal on 10 November 2025, which was two days before the end of the period for doing so. Cosette then filed its notice of appeal on 15 January 2026, which was the last day for doing so under the rules. The dates for the hearing of the appeal were fixed for a time to accommodate the convenience of Cosette’s senior counsel, which was not as early as the appeal might have otherwise been fixed. Over this period, Cosette knew that Mayne was threatening to bring proceedings concerning the alleged breaches of the SID and for the alleged wrongdoing by Cosette and others in the communication with the Treasurer.

5. [41]

   Cosette could have advanced the appeal faster than it did. It did not fail to take steps in accordance with the timelines stipulated by the Court’s rules, but nor did it take any steps to have the appeal commenced and brought on quickly.

6. [42]

   I do not consider it to be a decisive or even a particularly weighty matter, but I accept that a further consideration that weighs in the balance against a stay is that the prejudice to which the Cosette parties point is occasioned by the fact that Cosette’s appeal will not be determined until after 3 June 2026 in circumstances where the timing of the appeal is partly explained by the fact that Cosette did not move promptly to launch and prosecute its appeal.

7. [43]

   Mayne also pointed to an alleged delay in bringing the application for a stay. If there was any delay in making the application for a stay, it was a delay of a week. I do not consider that to be a delay of sufficient moment to weigh in the overall balance.

Conclusion

1. [44]

   For those reasons, the application for an interim stay is dismissed with costs.