Contract Law

What Makes a Valid Contract?

A Leading Case – The Carbolic Smoke Ball

Much of the law as to what defines an enforceable contract was established in what we call a leading case. It concerns a quaint piece of 19th Century quackery which was offered to the market, foolishly with a reward to anyone who it didn’t work for. Lawyers across the common law world remember it from their uni days, and its well worth studying.


In Carlill v Carbolic Smoke Ball Co[1] Mrs Carlill bought a carbolic smoke ball – a piece of rubber intended to be burned, while the user inhales the smoke. She used it as stipulated, on the promise in the advertisement that it would prevent colds, influenza and similar. But she contracted influenza in spite of the treatment.


Mrs Carlill claimed her £100 reward, but the company refused, claiming it was only an advertisement. She sued and took the appeal as far as the House of Lords (equivalent to the High Court – which was affordable in those days). Mrs Carlill won the appeal....





[1] Carlill v Carbolic Smoke Ball Co [1893] 1 QB 256.