CA-2025-002338 - [2025] EWCA Civ 1264

The Secretary of State does not dispute that the decision of the Judge was a discretionary decision and that the grounds on which this court can interfere with it are therefore limited. It does not matter whether or not we would have made this order, or whether another judge would have done. The narrow question for us is whether the Judge made an error of law or of principle or made a decision which no reasonable judge could have made in the circumstances. See the speech of Lord Diplock in Hadmor Productions v Hamilton [1983] AC 191 at p 229A-F, with which the other members of the Appellate Committee agreed. We must also give considerable leeway to the Judge, not only because this was a discretionary decision, but also because of the circumstances in which he made it. He had had no time, before the hearing started, to read the decision which is at the heart of the case, and had to rise during the hearing to read it. He had very limited time to absorb and reflect on the materials and submissions, and the Secretary of State’s position changed during the hearing. We should, for those reasons, give the Judge the benefit of any doubt. Having analysed the grounds of appeal, however, there is no relevant doubt. We have no hesitation in deciding that none of them is arguable with a realistic prospect of success.

The approach to questions of interim relief is set out in American Cyanamid Co v Ethicon Limited [1975] AC 396 (“American Cyanamid”).

Lord Diplock gave the leading speech in American Cyanamid. The other members of the Committee agreed with it. That appeal, in a patent dispute, concerned the test for the grant of what was then called an interlocutory injunction. The judge and this Court had held that the Appellant had to show a “prima facie” case that its patent had been infringed. Applying that test, the judge and this Court had reached opposite conclusions. As Lord Diplock explained, this Court had effectively tried the action, but on the basis of written evidence only, and with no cross-examination. He considered that the same principles applied to patent claims as to other actions (p 406B).

Lord Diplock referred to the practice that the grant of an interlocutory injunction was made subject to the plaintiff’s cross-undertaking in damages (p 406D-E). He explained that the purpose of an interlocutory injunction is to protect a claimant “against injury by violation of his legal right for which he could not be adequately compensated in damages” if his claim were to succeed at trial; but his need “for such protection must be weighed against the corresponding need of the defendant to be protected against injustice resulting from his having been prevented from exercising his own legal rights for which he could not be adequately compensated under the plaintiff’s undertaking in damages if” the defendant succeeded at trial (emphasis added). “The court must weigh one need against another and determine where ‘the balance of convenience’ lies”.

Lord Diplock invited the Appellate Committee to decide that in such cases a court need only be satisfied that “the claim is not frivolous or vexatious; in other words, that there is a serious question to be tried” (p 407G). The court should not at the interim stage “try to resolve conflicts of evidence on affidavits as to facts on which the claims of either party may ultimately depend nor to decide difficult questions of law which call for detailed argument and mature considerations”. Those were for the trial. “Unless the material available to the court at the hearing of injunction fails to disclose that the plaintiff has any real prospect of succeeding in his claim for a permission injunction at trial, the court should go on to consider whether the balance of convenience” favoured the grant or refusal of an injunction (p 408B).

If the claimant could be compensated in damages for any loss he would suffer between the date of the application and trial if the injunction were not granted, and the defendant could pay them, then “however strong the plaintiff’s case appeared at that stage”, an injunction should not normally be granted. If the damages would not compensate the claimant for those losses in the event that the claim succeeded at trial, the court should then consider whether, if the defendant were to succeed, he would be adequately compensated by resort to the claimant’s cross-undertaking in damages. If the defendant could be compensated and the claimant could pay, there would be “no good reason on this ground to refuse the injunction” (p 408C-E).

If there was doubt about the adequacy of damages as a remedy for either party or both, “the question of balance of convenience arises”. It was “unwise” to try to list the relevant factors, “let alone to suggest the relative weight to be attached to them. These will vary from case” (p 408F). Where other factors seem to be evenly balanced, “it is a counsel of prudence to take such measures as are calculated to preserve the status quo”. If the defendant is injuncted temporarily from doing something which he has not done before, the only effect of the interlocutory injunction, if he succeeds at trial, is to postpone “the date at which he is able to embark upon a course of action which he has not previously found it necessary to undertake” whereas to interrupt an “established enterprise” would cause much more inconvenience (p 408G-H).

If the extent of uncompensatable disadvantage to each party would not differ widely, “it may not be improper to take into account in tipping the balance the relative strength of each party’s case” as revealed by the evidence at the hearing of the application. “This, however, should be done only where it is apparent upon the facts disclosed by the evidence as to which there is no credible dispute that the strength of one party’s case is disproportionate to that of the other party” (p 409B-C).

The application of that decision in the context of public law claims was considered in detail by this Court in R (Public and Commercial Services Union) v Secretary of State for the Home Department [2022] EWCA Civ 842.