## Facts

- Carbolic Smoke Ball Co. published an advertisement promising to pay £100 to any person who contracted influenza after using its “Carbolic Smoke Ball” as directed.
- The advertisement stated that £1000 had been deposited with a bank to show the company’s sincerity.
- Louisa Carlill bought a smoke ball and used it in accordance with the printed directions for the stated period.
- After using the product as directed, Carlill contracted influenza and claimed the advertised £100.
- The company refused to pay, arguing the advertisement was not contractually binding.
- The trial court entered judgment for Carlill for £100.
- The company appealed; the Court of Appeal affirmed and dismissed the appeal.

## Issues

1. Whether the advertisement was mere puffery or an offer made with intent to create legal relations.
2. Whether an advertisement can constitute a unilateral offer to the public rather than an invitation to treat.
3. Whether acceptance required separate notice to the company, or could occur by performance of the stated conditions.
4. Whether the terms were sufficiently certain to form a contract despite arguments about vagueness (including time limits).
5. Whether Carlill provided consideration for the promise of payment.

## Decision

- The Court of Appeal held the advertisement was a binding unilateral offer to the public.
- The court found intent to create legal relations, supported by the statement that £1000 had been deposited to show sincerity.
- The offer was accepted by performance: using the smoke ball as directed and then contracting influenza.
- No separate notification of acceptance was required because the offer invited acceptance by performance and did not stipulate notice.
- The terms were sufficiently definite when read objectively in context.
- Consideration existed in Carlill’s purchase and the inconvenience and effort of using the product as directed.
- Judgment for Carlill was affirmed; the company was liable for the £100.

## Legal Principles

- A commercial advertisement may constitute an offer, not merely puffery or an invitation to treat, when it objectively manifests a commitment to pay upon satisfaction of stated conditions.
- A unilateral offer may be made to the public and accepted by any person who performs the specified conditions.
- For unilateral contracts, acceptance may occur by performance without prior or separate communication of acceptance unless the offer requires notice.
- Contractual certainty requires terms to be reasonably clear in context; courts may infer practical details where the essential conditions are stated.
- Consideration may consist of payment and/or the offeree’s inconvenience or detriment incurred in performing the conditions of the offer.

## Conclusion

The Court of Appeal enforced the company’s advertised reward as a unilateral contract formed by Carlill’s performance, holding that the advertisement showed intent to be bound, required no separate notice of acceptance, contained sufficiently definite conditions, and was supported by consideration.


Carlill v. Carbolic Smoke Ball Co., [1893] 1 Q.B. 256 (C.A.)