United States v. North was a United States Supreme Court case that addressed the issue of whether a federal court had the authority to issue a writ of habeas corpus to a prisoner held in a state prison. The case involved a prisoner, William North, who was convicted of murder in the state of Virginia and sentenced to death. North filed a petition for a writ of habeas corpus in the United States Circuit Court for the Eastern District of Virginia, claiming that his conviction was unconstitutional. The Circuit Court granted the writ and ordered North released from prison. The United States government appealed the Circuit Court's decision to the Supreme Court, arguing that the Circuit Court did not have the authority to issue the writ of habeas corpus. The Supreme Court agreed with the government, ruling that the Circuit Court did not have the authority to issue the writ of habeas corpus. The Court held that the writ of habeas corpus was a state prerogative and that the federal courts could not interfere with the state's power to enforce its criminal laws. The Court also held that the writ of habeas corpus could only be issued by a federal court if the prisoner was held in federal custody.

In United States v. North, the Supreme Court was asked to decide whether a federal statute that authorized the Secretary of War to appoint officers in certain volunteer regiments applied retroactively. The majority opinion held that it did not apply retroactively and thus could not be used as authority for an officer's appointment prior to its enactment. Justice Field dissented from this decision, arguing that Congress had intended for the statute to have retrospective effect and should therefore be interpreted accordingly. He argued further that if Congress had meant otherwise they would have explicitly stated so in their language or provided some other indication of their intent regarding retroactivity. In conclusion, he argued that since there was no such indication present here, then it must be assumed by default that Congress intended for the law to apply retrospectively and thus any appointments made under its authority were valid regardless of when they occurred before or after its passage into law.