American Cyanamid Co v Ethicon Ltd [1975] AC 396 is a landmark case in English civil procedure law, concerning the conditions for granting an interim injunction. An interim injunction is a temporary order that prevents a party from doing something until the final resolution of the case.
The case involved a dispute over a patent for artificial absorbable surgical sutures, which are used to stitch wounds and dissolve over time. The claimant, American Cyanamid, held the patent and sued the defendant, Ethicon, for infringing it by launching a similar product in the UK market. The claimant sought an interim injunction to stop the defendant from selling the product until the trial.
The main issue was what the claimant had to prove to obtain an interim injunction. The Court of Appeal held that the claimant had to show a prima facie case of infringement, meaning that there was a strong likelihood of success at trial. The Court of Appeal discharged the injunction, finding that the claimant had not established a prima facie case.
The House of Lords reversed the decision and reinstated the injunction. The House of Lords laid down a new test for granting an interim injunction, which is still followed today. The test consists of four steps:
- The claimant must show that there is a serious issue to be tried, meaning that the claim is not frivolous or vexatious.
- The court must consider whether damages would be an adequate remedy for the claimant if they win at trial, or whether an injunction is necessary to protect their rights.
- If damages are not adequate, the court must consider whether the defendant would be adequately compensated by the claimant’s undertaking in damages if they win at trial, or whether an injunction would cause them irreparable harm.
- If there is any doubt about the adequacy of damages on either side, the court must weigh the balance of convenience between the parties, taking into account factors such as the merits of the case, the effect of granting or refusing the injunction, and the preservation of the status quo.
The House of Lords also emphasized that the court should not try to resolve disputed issues of fact or law at the interim stage, as this would usurp the function of the trial.
The relevance of this case is that it established a clear and flexible framework for deciding whether to grant an interim injunction in any type of case. It also recognized that an interim injunction is a discretionary remedy that should be granted with caution and only when it is just and convenient to do so. The case has been cited and applied in many subsequent cases involving interim injunctions in various fields of law¹²³⁴.
(1) American Cyanamid v Ethicon – LawTeacher.net. https://www.lawteacher.net/cases/american-cyanamid-v-ethicon.php.
(2) American Cyanamid v Ethicon – Case Summary – IPSA LOQUITUR. https://ipsaloquitur.com/civil-procedure/cases/american-cyanamid-v-ethicon/.
(3) U.K., American Cyanamid Co. v. Ethicon Ltd., [1975] AC 396. https://globalfreedomofexpression.columbia.edu/laws/u-k-american-cyanamid-co-v-ethicon-ltd-1975-ac-396/.
(4) American Cyanamid Co v Ethicon Ltd – Wikipedia. https://en.wikipedia.org/wiki/American_Cyanamid_Co_v_Ethicon_Ltd.
(5) undefined. https://www.lawteacher.net/cases/american-cyanamid-v-ethicon.php?vref=1.
Law Author 