Stilk v Myrick [1809] EWHC KB J58 is an English contract law case heard in the King's Bench on the subject of consideration. In his verdict, the judge, Lord Ellenborough decided that in cases where an individual was bound to do a duty under an existing contract, that duty could not be considered valid consideration for a new contract. It has been distinguished from Williams v Roffey Bros & Nicholls (Contractors) Ltd, which suggested that situations formerly handled by consideration could instead be handled by the doctrine of economic duress.

Williams v Roffey Bros & Nicholls (Contractors) Ltd [1989] EWCA Civ 5 is a leading English contract law case. It decided that in varying a contract, a promise to perform a pre-existing contractual obligation will constitute good consideration so long as a benefit is conferred upon the 'promiseor'. This was a departure from the previously established principle that promises to perform pre-existing contractual obligations could not be good consideration.