United States v. Minor is a United States Supreme Court case that dealt with the issue of whether a federal court had the power to issue a writ of habeas corpus to a state court. The case involved a man named Minor, who had been convicted of a crime in a state court and was seeking to have his conviction overturned. The Supreme Court held that the federal court did not have the power to issue a writ of habeas corpus to a state court. The Court reasoned that the writ of habeas corpus was a remedy that was available only to federal courts, and that the state court had the power to decide the case on its own merits. The Court also noted that the writ of habeas corpus was not intended to be used as a substitute for a trial in a state court. The Court's decision in United States v. Minor was significant because it established that the federal court did not have the power to issue a writ of habeas corpus to a state court. This decision has been cited in numerous subsequent cases, and it has been used to support the idea that the writ of habeas corpus is a remedy that is available only to federal courts.

In United States v. Minor, the Supreme Court was asked to decide whether a federal statute that required all persons over 21 years of age who had not previously registered for military service to register within 30 days was constitutional. Justice Field dissented from the majority opinion and argued that Congress did not have the power under Article I, Section 8 of the Constitution to pass such a law because it exceeded its authority in regulating militia forces. He further argued that even if Congress had this power, it could only be exercised when there is an actual need for additional troops due to war or other emergency situations. Since no such situation existed at the time of passage, he concluded that Congress acted beyond its powers by passing this law and thus violated both state sovereignty and individual rights protected by the Fifth Amendment's Due Process Clause.