American Cyanamid Co. v. Ethicon Ltd.
Rule established
At interlocutory stage, the court should not resolve contested questions of fact or law; it need only satisfy itself there is a serious question to be tried, then consider balance of convenience. Widely adopted in Indian courts alongside the Dalpat Kumar test.
Facts
- American Cyanamid (patent holder) sought interlocutory injunction to restrain Ethicon from selling allegedly infringing absorbable surgical sutures
- The trial court examined the merits in detail and refused the injunction, finding no prima facie case
- The matter reached the House of Lords on the proper approach to interlocutory injunctions
Issue
- What is the correct approach for courts when considering interlocutory injunctions: should they resolve merits or only assess threshold viability?
Held
- At interlocutory stage, the court should not try to resolve contested questions of fact or law
- The threshold is low: "serious question to be tried" (not probability of success)
- Once the threshold is met, the court considers balance of convenience
- The guiding principle is: which course carries the lesser risk of injustice if the court turns out to be wrong?
- If damages would be an adequate remedy for the plaintiff, no injunction should be granted
Ratio Decidendi
Interlocutory injunctions require only a "serious question to be tried" (not prima facie case in the strong sense). Beyond that threshold, balance of convenience determines the outcome.
How to use it in an exam
- Key line: "In American Cyanamid (1975), the House of Lords held that at interlocutory stage, courts should not resolve merits. The threshold is 'serious question to be tried'; then balance of convenience decides. Indian courts apply this alongside Dalpat Kumar."
Source
Source: [1975] AC 396
This is an educational summary, not the judgment itself. Cite the reported version in professional or academic work.