Carlill v Carbolic Smoke Ball Co [1893] 1 QB 256
Carlill v Carbolic Smoke Ball Co is the leading authority on unilateral offers made to the public. It explains when an advertisement can amount to a contractual promise and how such an offer may be accepted through performance.
Facts
The Carbolic Smoke Ball Company advertised that it would pay £100 to anyone who contracted influenza after using its smoke ball three times daily for two weeks in accordance with the printed directions. The advertisement stated that £1,000 had been deposited with the Alliance Bank to show the company's sincerity. Mrs Carlill obtained a smoke ball and used it as directed, but nevertheless caught influenza. She claimed the promised £100. The company refused to pay, arguing that the advertisement was promotional language rather than a binding offer. It also contended that the terms were too uncertain, that Mrs Carlill had not notified the company of her acceptance before using the product, and that she had provided no consideration for the promise.
Legal Issue
Did the advertisement amount to a legally binding offer capable of acceptance by anyone who performed its conditions, and could Mrs Carlill accept it without first communicating her intention to the company?
Held
The Court of Appeal held that the company was contractually bound to pay Mrs Carlill £100. Read objectively, the advertisement was a unilateral offer to anyone who performed its stated conditions, not merely an invitation to treat or advertising puff. The reference to the £1,000 bank deposit showed a serious intention to be bound. Mrs Carlill accepted the offer by using the smoke ball as directed; because the offer invited acceptance by complete performance, separate advance notification of acceptance was unnecessary. Her use of the product supplied consideration because she undertook the requested inconvenience, while the company stood to benefit commercially from increased confidence in and use of its product. The promise was sufficiently certain to be enforced on the facts.
⭐ Legal Principle
A clear advertisement may constitute a unilateral offer to the world where it objectively shows an intention to be bound. If the offer calls for acceptance by performing specified conditions, a person accepts by completing them and need not separately notify the offeror before performance, unless the offer requires notification.
Significance
The case is a foundation of the law on offer and acceptance. It shows why most advertisements are invitations to treat, as in Partridge v Crittenden, while unusually definite reward promises may be offers. It also establishes that objective intention matters more than an advertiser's unexpressed intentions and that a unilateral offer can dispense with prior communication of acceptance. The decision remains central when analysing reward cases, promotional promises and acceptance by conduct.
Common exam questions about this case
Why was the advertisement in Carlill treated as an offer rather than an invitation to treat?
The advertisement contained a definite promise to pay £100 to anyone who used the smoke ball as directed and still contracted influenza. Its statement that £1,000 had been deposited with a bank objectively demonstrated seriousness. The Court of Appeal therefore treated it as an offer inviting acceptance by performance, unlike an ordinary advertisement that merely invites customers to make offers to buy.
Why did Mrs Carlill not have to communicate acceptance before using the smoke ball?
The offer was unilateral: it requested performance of specified conditions rather than a return promise. On an objective reading, the company did not require users to notify it before beginning performance. Mrs Carlill accepted when she completed the requested use of the smoke ball. The case does not create a general rule that acceptance need never be communicated; the result depends on the form and terms of the offer.
What consideration supported the company's promise to pay the reward?
Mrs Carlill incurred the inconvenience of using the smoke ball in the prescribed way, which was the conduct requested by the company. The company also expected a commercial benefit because the advertisement would promote confidence in the product and encourage its use and sale. Either analysis supported the conclusion that her performance was not gratuitous and supplied consideration for the reward promise.