In Allen v. Massey, the United States Supreme Court was asked to decide whether a contract between two parties was valid and enforceable. The contract in question was an agreement between Allen and Massey, in which Allen agreed to pay Massey a certain sum of money in exchange for Massey's promise to convey certain real estate to Allen. The Supreme Court held that the contract was valid and enforceable, and that Allen was entitled to the real estate. The Court reasoned that the contract was valid because it was supported by consideration, meaning that both parties had given something of value in exchange for the other's promise. In this case, Allen had given Massey money, and Massey had given Allen a promise to convey the real estate. The Court also held that the contract was enforceable, meaning that Allen could sue Massey for breach of contract if Massey failed to fulfill his promise. Ultimately, the Supreme Court held that the contract between Allen and Massey was valid and enforceable, and that Allen was entitled to the real estate. This decision established that contracts supported by consideration are valid and enforceable, and that parties to such contracts can sue for breach of contract if the other party fails to fulfill their promise.

Justice Field delivered the dissenting opinion in Allen v. Massey, arguing that the majority's decision was contrary to both law and justice. He argued that a contract between two parties should be enforced according to its terms, regardless of any subsequent changes in circumstances or laws. In this case, he noted that when the contract was made it provided for payment of interest on overdue payments at a rate specified by state law; however, after default had occurred and before suit was brought against Massey for nonpayment of principal and interest due under the contract, Congress passed an act reducing such rates from 10% per annum to 7%. Justice Field argued that since no new agreement had been entered into between Allen and Massey regarding this change in rate of interest due on overdue payments - which would have been necessary if they wished to modify their original agreement - then it must stand as originally written with respect to all matters not otherwise altered by operation of law. Therefore he concluded that Allen should receive judgment against Massey for 10% annual interest upon his claim until paid off rather than 7%, as determined by the majority opinion.