Home > West's Encyclopedia of American Law > Bilateral Contract

An agreement formed by an exchange of a promise in which the promise of one party is consideration supporting the promise of the other party.

A bilateral contract is distinguishable from a unilateral contract, a promise made by one party in exchange for the performance of some act by the other party. The party to a unilateral contract whose performance is sought is not obligated to act, but if he or she does, the party that made the promise is bound to comply with the terms of the agreement. In a bilateral contract both parties are bound by their exchange of promises.

Both parties to a bilateral contract make promises. With respect to the promise in issue, the party making the promise is the promisor and the other party is the promisee. The legal detriment incurred by the promisee consists of a different promise by him or her to do something or refrain from doing something that he or she was not previously legally obligated...