Interim Injunction in UK Law

As to what degree of likelihood makes the prospects of success 'sufficiently favourable', the general approach should be that courts will be exceedingly slow to make interim restraint orders where the applicant has not satisfied the court he will probably ('more likely than not') succeed at the trial.

The assessment is made upon the same basis as damages for breach of contract would be assessed if the undertaking had been a contract between the plaintiff and the defendant, that the plaintiff would not prevent the defendant from doing that which he was restrained from doing by the terms of the injunction.

If the legislature intended to give the court jurisdiction to grant interim injunctions against the Crown, it is difficult to think of any reason why the jurisdiction should be available only in judicial review proceedings and not in civil proceedings as defined in the Act of 1947. Hence, an enactment which in terms applies only to the forms of final relief available in judicial review proceedings cannot possibly have been so intended.

In this context, particular stress should be placed upon the importance of upholding the law of the land, in the public interest, bearing in mind the need for stability in our society, and the duty placed upon certain authorities to enforce the law in the public interest. This is of itself an important factor to be weighed in the balance when assessing the balance of convenience.

In the end, the matter is one for the discretion of the court, taking into account all the circumstances of the case. Even so, the court should not restrain a public authority by interim injunction from enforcing an apparently authentic law unless it is satisfied, having regard to all the circumstances, that the challenge to the validity of the law is, prima facie, so firmly based as to justify so exceptional a course being taken.

A right to obtain an interlocutory injunction is not a cause of action. It is dependent upon there being a pre-existing cause of action against the defendant arising out of an invasion, actual or theatened by him, of a legal or equitable right of the plaintiff for the enforcement of which the defendant is amenable to the jurisdiction of the court. The right to obtain an interlocutory injunction is merely ancillary and incidental to the pre-existing cause of action.

Where, however, the grant or refusal of the interlocutory injunction will have the practical effect of putting an end to the action because the harm that will have been already caused to the losing party by its grant or its refusal is complete and of a kind for which money cannot constitute any worthwhile recompense, the degree of likelihood that the plaintiff would have succeeded in establishing his right to an injunction if the action had gone to trial, is a factor to be brought into the balance by the judge in weighing the risks that injustice may result from his deciding the application one way rather than the other.