Boyd v. Wyly is a United States Supreme Court case that was decided in 1887. The case involved a dispute between two parties over the ownership of a piece of property. The plaintiff, Boyd, claimed that he had purchased the property from the defendant, Wyly, and that Wyly had failed to deliver the deed to the property. Wyly argued that he had never sold the property to Boyd and that the deed was never delivered. The Supreme Court held that Wyly was liable for breach of contract and that Boyd was entitled to the deed to the property. The Court found that Wyly had made a promise to deliver the deed and that he had failed to do so. The Court also held that Wyly was liable for damages for his breach of contract. The Court's decision in Boyd v. Wyly established that a party who makes a promise to deliver a deed is liable for damages if they fail to do so. This decision has been cited in numerous cases since then and has become an important precedent in contract law.

Justice Field delivered the dissenting opinion in Boyd v. Wyly, arguing that the majority's decision was contrary to established precedent and would have a far-reaching impact on commerce between states. He argued that it was not within Congress' power to regulate interstate commerce by allowing individuals from one state to sue citizens of another state in their own courts for debts incurred while conducting business across state lines. Furthermore, he noted that if such suits were allowed, they could be used as a means of harassment or extortion against out-of-state defendants who had no recourse but to appear before an unfamiliar court with unfamiliar laws and procedures. Justice Field concluded his dissent by noting that this case should have been decided according to existing law rather than creating new rules which could lead to further confusion and uncertainty regarding interstate commercial transactions.