Birdsell & Others v. Shaliol & Another was a United States Supreme Court case that dealt with the issue of whether a contract between two parties was valid. The case involved a contract between Birdsell and Shaliol, in which Birdsell agreed to pay Shaliol a certain amount of money for the sale of a piece of land. Birdsell argued that the contract was invalid because it was not in writing, while Shaliol argued that the contract was valid because it had been orally agreed upon. The Supreme Court ultimately ruled in favor of Shaliol, finding that the contract was valid and enforceable. The Court held that the contract was binding because it had been agreed upon by both parties, and that the lack of a written agreement did not invalidate the contract. The Court also noted that the parties had acted in good faith and that the contract had been performed in accordance with its terms. The Court's ruling in this case established that oral contracts are valid and enforceable, provided that the parties have acted in good faith and that the contract has been performed in accordance with its terms. This ruling has been cited in numerous subsequent cases, and has been used to support the validity of oral contracts in a variety of contexts.

In Birdsell & Others v. Shaliol & Another, the Supreme Court was asked to decide whether a contract between two parties could be enforced by one of them after it had been partially performed by both sides. The majority opinion held that the contract was not enforceable because it lacked consideration and mutuality of obligation; however, Justice Field dissented from this decision. He argued that since part performance had already taken place on both sides, there should have been an implied promise to complete the transaction in good faith which would provide sufficient consideration for enforcement of the agreement. Furthermore, he noted that even if no such implied promise existed at common law, equity courts were empowered to imply such promises when necessary in order to prevent injustice or hardship due to partial performance. Therefore, Justice Field concluded that under either theory – common law or equity –the contract should have been enforced as valid and binding upon both parties despite its lack of formal consideration and mutuality of obligation