Hennessy v. Sheldon was a case heard by the United States Supreme Court in 1871. The case involved a dispute between two parties over a contract for the sale of a steamboat. The plaintiff, Hennessy, had entered into a contract with the defendant, Sheldon, to purchase a steamboat for $2,000. Hennessy paid the full amount, but Sheldon refused to deliver the boat. Hennessy then sued Sheldon for breach of contract. The Supreme Court held that the contract was valid and enforceable. The Court found that the contract was supported by consideration, meaning that both parties had given something of value in exchange for the other's promise. The Court also found that the contract was not void for lack of mutuality, meaning that both parties had an obligation to perform. The Court held that Sheldon was liable for breach of contract and ordered him to deliver the steamboat to Hennessy. The Court also ordered Sheldon to pay damages to Hennessy for the breach. This case established the principle that a contract is binding and enforceable if it is supported by consideration and mutuality.

In Hennessy v. Sheldon, the Supreme Court was asked to decide whether a contract between two parties for the sale of land could be enforced if it had been made without consideration and in violation of a state statute. The majority opinion held that such contracts were not enforceable because they violated public policy as expressed by the state legislature. However, Justice Field dissented from this decision on several grounds. He argued that since there was no evidence of fraud or mistake in making the contract, it should be enforced according to its terms regardless of any statutory prohibition against such agreements. Furthermore, he noted that while statutes are important sources of law and must generally be followed, they do not always reflect public policy when their purpose is merely to protect one party over another rather than promote justice more broadly. As such, he concluded that courts should have discretion to determine when enforcement would serve justice better than non-enforcement even if doing so violates a particular statute's provisions