Consideration

The exchange of value that makes a promise legally enforceable

Overview

Common law requires consideration, something of legal value bargained for, to enforce a promise, distinguishing contracts from gifts and idle undertakings. The doctrine demands benefit to the promisor or detriment to the promisee, and past consideration does not count. Its classic puzzles include peppercorn nominal bargains and contract modification, resolved differently by different courts. Civil law systems need only cause or intent, and American law softened the edge through promissory estoppel, making consideration a signature common law doctrine. Civilian systems achieve similar results through concepts of cause and lesion, protecting reliance rather than bargain.