The United States v. John Goodwin was a Supreme Court case in which the defendant, John Goodwin, had been convicted of piracy and sentenced to death by a circuit court. The government argued that under the Judiciary Act of 1789, Congress had given federal courts exclusive jurisdiction over cases involving crimes committed on the high seas. However, Goodwin contended that he should have been tried in state court because his alleged crime occurred within three miles of shore—an area traditionally considered part of a state's territorial waters rather than subject to federal jurisdiction. In an 8-1 decision written by Chief Justice Marshall, the Supreme Court held that Congress did indeed have authority to define maritime offenses as it saw fit and thus could grant exclusive jurisdiction over such matters to federal courts even if they took place close inshore. As such, Goodwin's conviction was upheld and he remained liable for execution according to law.

In the case of The United States v. John Goodwin, the Supreme Court was tasked with deciding whether a federal court had jurisdiction over an indictment for piracy and murder that occurred on board a vessel in international waters. Justice Johnson wrote a dissenting opinion arguing that Congress did not have authority to pass laws governing conduct occurring outside of U.S. territorial waters or beyond its jurisdictional boundaries, as this would be an unconstitutional exercise of power by Congress under Article I Section 8 Clause 10 of the Constitution which grants only limited powers to regulate commerce between foreign nations and among states within the Union. He argued that since no act committed by Goodwin could be considered "piracy" until it was defined as such by statute, he should not be held accountable for his actions unless they were specifically prohibited at common law prior to passage of any relevant statutes; otherwise, punishing him would amount to ex post facto legislation which is forbidden under Article I Section 9 Clause 3 of the Constitution.