United States v. Saunders was 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 Saunders who had been convicted of murder in a state court and was sentenced to death. He then filed a petition for a writ of habeas corpus in a federal court, claiming that his conviction was unconstitutional. The federal court granted the writ and ordered the state court to release Saunders. The United States Supreme Court held that the federal court did not have the power to issue the writ of habeas corpus. The Court reasoned that the writ of habeas corpus was a remedy that was available only to federal courts, and that the federal court did not have the power to interfere with the state court's decision. The Court also noted that the writ of habeas corpus was not available to challenge the constitutionality of a state court's decision. The Court's decision in United States v. Saunders established that federal courts do not have the power to issue writs of habeas corpus to state courts. This decision has been cited in numerous cases since then, and it remains an important precedent in the area of federal-state relations.

In United States v. Saunders, the Supreme Court was tasked with determining whether a federal statute that allowed for the sale of public lands to settlers who had occupied and improved them prior to 1866 was constitutional. The majority opinion held that Congress did not have authority under Article IV, Section 3 of the Constitution to pass such a law as it would be an unconstitutional taking without just compensation. Justice Field dissented from this ruling on two grounds: firstly, he argued that Congress had acted within its power in passing this law because Article IV grants broad powers over public land; secondly, he argued that even if there was some doubt about Congressional authority in this case, any doubts should be resolved in favor of upholding Congressional action due to long-standing precedent and practice which has been accepted by all branches of government since 1790. Ultimately Justice Field concluded that while it may not have been wise or prudent for Congress to enact such legislation without providing just compensation for those affected by it, they were still acting within their Constitutional powers when doing so.