Interim Injunctions – American Cyanamid Test & CPR Practice

Interim Injunctions

Procedural basis: CPR Part 25 (interim remedies); s.37 Senior Courts Act 1981 (jurisdiction).

The American Cyanamid Test

The leading authority is American Cyanamid Co v Ethicon Ltd [1975] AC 396, which set out a three-stage test:

1. Serious question to be tried — the claim must not be frivolous or vexatious; the court does not assess the merits in depth at this stage.
2. Adequacy of damages — would damages be an adequate remedy for the claimant if refused an injunction? If yes, an injunction will generally be refused. Conversely, if damages would adequately compensate the defendant for being wrongly enjoined, that favours granting the injunction.
3. Balance of convenience — if the above factors are evenly balanced, the court preserves the status quo.

Key Modifications & Exceptions

• Where trial is unlikely or the injunction would effectively determine the dispute, the court will look more closely at the relative merits.
• Defamation claims: freedom of expression under s.12 Human Rights Act 1998 means the court must be satisfied the claimant is likely to succeed at trial before restraining publication.
• Mandatory injunctions (requiring positive action) attract a higher threshold — the court asks whether there is a strong prima facie case.

Cross-Undertaking in Damages

• The applicant must almost always give a cross-undertaking in damages — a promise to compensate the respondent if the injunction was wrongly granted. The court may require security.

Procedural Points (CPR)

• Applications are made under CPR r.25.1 and usually supported by evidence (witness statement).
• Without-notice (ex parte) applications are permitted where giving notice would defeat the purpose — but full and frank disclosure of all material facts is required (duty of candour).
• The order must include a return date so the respondent can be heard.

Exam Tip

On SQE1 facts, work through the three American Cyanamid stages in order — a common trap is jumping to 'balance of convenience' without first considering whether damages would suffice.