Unilateral Contract CASES
In English law, a unilateral contract involves one party making a promise or offer that becomes binding only when another party completes a specified action or performance.
Definition and Principles
Unilateral contracts differ from bilateral contracts because acceptance occurs through performance rather than a reciprocal promise. The promisor is bound to fulfil their obligation once the specified action is completed by the promisee.
Common Examples
- Reward offers (e.g., for returning lost items).
- Promotional contests (e.g., prize awarded upon completing specific actions).
Key Case
Carlill v Carbolic Smoke Ball Co (1893): A landmark case establishing enforceability of unilateral contracts when a person acts upon an advertised promise.
Practical Implications
Parties offering unilateral contracts must clearly state terms and conditions, as acceptance and contract formation occur immediately upon performance of the specified act.
Importance
Understanding unilateral contracts ensures clarity in contractual obligations, particularly for promotional offers, competitions, and reward arrangements.
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The defendant offered a £20 reward for information leading to the discovery of his brother's murderer. The claimant provided the information, motivated by a desire to ease her conscience while believing she was dying, and successfully claimed the reward. Facts In April 1831, the defendant, Mr William Carwardine, published a handbill offering a reward of £20 to any person who would provide information that would lead to the discovery of the murderer of his brother, Walter Carwardine. The plaintiff, Mary Anne Williams, was aware of the offer. In August 1831, the plaintiff, having been beaten and bruised by a man
A company accepted a tender to supply goods at fixed prices for a year. The tenderer later refused to fulfil a specific order. The court held the tender was a standing offer which was converted into a binding contract by each specific order. Facts The Great Northern Railway Co (the plaintiffs) advertised for tenders for the supply of various stores, including iron, for a period of twelve months from 1 November 1871. Mr Witham (the defendant) submitted a tender in which he offered to supply the company with specified articles, at specified prices, for the twelve-month period in “such quantities
A father promised his son and daughter-in-law a house if they paid the mortgage. After his death, his personal representatives sought to evict her. The court found a unilateral contract, holding the father's promise was irrevocable as long as performance continued. Facts In 1936, a father bought a house in Newcastle-upon-Tyne for his son and daughter-in-law to live in. The house was put in the father’s name. He paid £250 of the £750 purchase price in cash and borrowed the remaining £500 from a building society, secured by a mortgage on the property. The father told his daughter-in-law that the
A property seller offered to exchange contracts if the buyer attended with a signed contract and deposit cheque. The buyer complied, but the seller refused to proceed. The court held a binding unilateral contract existed, which the seller breached by revoking their offer. Facts The plaintiffs, Dahlia Ltd, negotiated to purchase properties from the first defendants, Four Millbank Nominees Ltd. The essential terms were agreed. The defendants’ solicitors wrote to the plaintiffs’ solicitors stating they were instructed to proceed. Crucially, the defendants’ representative orally informed the plaintiffs that if they attended the defendants’ office with a counterpart contract signed by
Established principles of unilateral contracts and acceptance by conduct.
