The United States v. John D. Quincy was a Supreme Court case in which the defendant, John D. Quincy, had been convicted of violating the Non-Intercourse Act of 1809 by trading with an enemy nation without permission from Congress or President James Madison. The court held that while it was true that no specific penalty for such an offense had been provided for in the act itself, this did not mean that Congress could not pass laws to punish those who violated its provisions and thus affirmed Quincy's conviction on appeal. Furthermore, they found that since he had acted willfully and knowingly against the law as written at the time of his actions, he should be punished accordingly despite any lack of clarity regarding penalties within said statute.

In the United States v. John D. Quincy, the Supreme Court was tasked with determining whether a federal court had jurisdiction to try an individual for piracy on the high seas when they were not apprehended within U.S. waters or by a U.S vessel but instead by another nation's ship and brought into their own port for trial before being transferred to American custody and tried in a federal court of law in Massachusetts where he was convicted of piracy under admiralty law. The majority opinion held that since Congress had given authority to courts of admiralty over cases involving crimes committed on the high seas, regardless of where they were captured, it did have jurisdiction over this case as well as any other similar ones that may arise in future instances; however Justice Story dissented from this decision arguing that while Congress could grant such powers to courts of admiralty, there must be some limits placed upon them so as not to infringe upon international laws regarding sovereignty which would otherwise prevent foreign nations from apprehending individuals who commit acts against them outside their territorial boundaries without fear of interference from other countries' judicial systems or governments themselves taking matters into their own hands rather than seeking redress through diplomatic channels first before resorting to legal action if necessary at all afterwards..