The law of contracts has various rules to determine whether obligations have been discharged. Of course, if both parties have fully performed the contract, duties will have terminated. But many duties are subject to conditions, including conditions precedent and subsequent, conditions requiring approval of the promisee or someone else, and clauses that recite time to be of the essence.
A contract obligation may be discharged if the promisor has not received the benefit of the promisee’s obligation. In some cases, failure to carry out the duty completely will discharge the corresponding obligation (material breach); in other cases, the substantial performance doctrine will require the other party to act.
A contract may have terminated because one of the parties tells the other in advance that he will not carry out his obligations; this is called anticipatory breach. The right to adequate assurance allows one party to determine whether the contract will be breached by the other party.
There are other events, too, that may excuse performance: impracticability (including the UCC rules governing impracticability in contracts for the sale of goods), death or incapacity of the obligor, destruction of the thing necessary for the performance, government prohibition, frustration of purpose, and power of avoidance.
Finally, note that not all obligations are created by contract, and the law has rules to deal with discharge of duties in general. Thus, in the appropriate cases, the obligee may cancel or surrender a written contract, may enter into an accord, may agree to rescind the agreement, or may release the obligor. Or the obligor may show a material alteration in the contract, may become bankrupt, or may plead the statute of limitations—that is, plead that the obligee waited too long to sue. Or the parties may, by word or deed, mutually abandon the agreement. In all these ways, duties may be discharged.
A condition precedent
If Al and Betty have an executory contract, and if Betty tells Al that she will not be fulfilling her side of the bargain,
Jack contracts with Anne to drive her to the airport Wednesday afternoon in his specially designed stretch limousine. On Wednesday morning Jack’s limousine is hit by a drunken driver, and Jack is unable to drive Anne. This is an example of
Jack is ready and willing to drive Anne to the airport. But Anne’s flight is cancelled, and she refuses to pay. This is an example of