In the law of contracts, the destruction of the value of the performance that has been bargained for by the promisor as a result of a supervening event.
Frustration of purpose has the effect of discharging the promisor from his or her obligation to perform, in spite of the fact that performance by the promisee is possible, since the purpose for which the contract was entered into has been destroyed. For example, an individual reserves a hall for a wedding. In the event that the wedding is called off, the value of the agreement would be destroyed. Even though the promisee could still literally perform the obligation by reserving and providing the hall for the wedding, the purpose for which the contract was entered into was defeated. Apart from a nonrefundable deposit fee, the promisor is ordinarily discharged from any contractual duty to rent the hall.
In order for frustration to be used as a defense for nonperformance, the value of the anticipated counter performance must have been substantially destroyed and the frustrating occurrence must have been beyond the contemplation of the parties at the time the agreement was made.