Legal Case Summary
Hartley v Ponsonby [1857] 7 EL BL 872; 119 ER 1471
When performance of an existing duty can be consideration.
Facts
The defendant, Ponsonby, was captain of a ship on which the plaintiff was a sailor. The sailors contracted to serve on board the ship for a maximum of three years to any ports required until her return to the UK. While at sea, seventeen out of the total 37 crew deserted. The ship was left in a much more dangerous condition by the reduced crew. The captain, in order to persuade the remaining crew to man the vessel, promised them extra wages. When the vessel returned to the UK he refused to pay them. The plaintiff sued for breach of contract.
Issues
The defendant argued that the sailors had provided no consideration and that, therefore, the contract was void. He claimed the sailors were only doing what they were already obliged to do under the ship’s articles, which they had signed. They argued that according to Harris v Watson (1791) Peak Cas 72 in which it was held that a sailor was not owed extra wages in such a situation.
Decision / Outcome
Lord Campbell CJ said that Harris v Weston was authority that a sailor is expected to complete a voyage if there is an emergency, such as a large part of the crew being washed overboard. However, there was no such emergency here. The ship was in port and was only unseaworthy due to the lack of sufficient crewmembers. Therefore, the plaintiff was within his rights to refuse to put to sea. Consequently, by agreeing to do the work, the plaintiff supplied fresh consideration. Therefore, the contract was valid.
Updated 19 March 2026
This article accurately summarises the facts and legal principle established in Hartley v Ponsonby (1857). The core rule — that performance of an existing contractual duty can constitute good consideration where that performance goes beyond what was originally required, or where the circumstances have changed so substantially that the original duty no longer strictly applies — remains a foundational principle of English contract law.
Readers should note one minor inaccuracy in the article: the opposing authority is cited in the Facts section as Harris v Watson but referred to in the Decision section as Harris v Weston. The correct name is Harris v Watson (1791) Peake 102, and the reference to ‘Weston’ in the Decision section appears to be a typographical error.
The broader legal context remains current. The rule in Hartley v Ponsonby is typically taught alongside Stilk v Myrick [1809] 2 Camp 317 and the later Court of Appeal decision in Williams v Roffey Bros & Nicholls (Contractors) Ltd [1991] 1 QB 1, which significantly developed this area by holding that a promise to perform an existing contractual duty can constitute consideration where the promisor obtains a practical benefit. These cases together form the modern framework for this topic and are not displaced by any subsequent statutory change. No legislation has altered the common law position described in this article.
