Carlill v Carbolic Smoke Ball Co. [1893] is among the most important cases in English contract law. It is the leading authority on the treatment of unilateral offers, and for the principle that advertisements can constitute offers if sufficiently specific, in which case performance can amount to acceptance.

Facts of the Case

The defendant company placed an advertisement for its product, the carbolic smoke ball, promising to pay £100 to anyone who contracted influenza after using the product three times a day for two weeks as directed. To demonstrate their sincerity, the company stated that it had deposited £1,000 with its bank. The claimant, Mrs Carlill, purchased the smoke ball and used it as directed, but caught influenza and claimed the reward. The company refused to pay, arguing it had no contractual obligation to her.

Legal Issues

  • Whether the advertisement was a binding offer or a mere “advertising puff”.
  • Whether a contract could legally be made with the “whole world”.
  • Whether Mrs Carlill had to notify the company of acceptance before performing the conditions.
  • Whether there was valid consideration for the promise of the reward.

Judgement

The Court of Appeal unanimously held that the advertisement was a valid offer, which Mrs Carlill had accepted by fulfilling its conditions. The court rejected the “advertising puff” argument, noting that the £1,000 deposit was clear evidence of a serious contractual intent.

On notification, the court ruled that in this type of advertisement the offeror waives the right to be notified of acceptance; the contract is formed when the offeree performs the requested act. The court also held that an offer can be made to the entire world, becoming a contract with any individual who fulfils the terms. Finally, consideration existed both in the “inconvenience” Mrs Carlill suffered in using the product and in the benefit the company received from increased sales.

Authority

Carlill is the seminal authority for unilateral contracts, where one party makes a promise in exchange for the performance of an act. It establishes that:

  • Advertisements can be offers (rather than invitations to treat) if specific and demonstrating an intent to be bound.
  • In unilateral contracts, performance constitutes acceptance, and prior notification is generally not required.
  • An offer can be made to the “whole world”.

Related Discussion and Commentary

  • Consumer protection: the decision is often viewed as an early form of consumer protection, the court being unimpressed by an attempt to evade “extravagant promises” made to drive profit.
  • Offer vs. invitation to treat: contrasted with Partridge v Crittenden, where adverts for goods are generally invitations to treat because of limited supply; here the specific promise and bank deposit pointed to a binding offer.
  • Reliance interest: some commentators suggest the courts “stretched” offer, acceptance, and consideration to protect Mrs Carlill’s reliance on the company’s public promises.
  • Certainty and intent: the case underscores that the objective appearance of intent (the £1,000 deposit) matters more than the claimant’s subjective intention.