Betts v. Mugridge was a United States Supreme Court case that dealt with the issue of whether a state court had the authority to issue a writ of habeas corpus to a prisoner who was being held in a federal prison. The case arose when a prisoner, Betts, was held in a federal prison in the state of New York. Betts sought a writ of habeas corpus from the state court, claiming that he was being held in violation of his constitutional rights. The state court granted the writ, and the federal government appealed the decision to the Supreme Court. The Supreme Court held that the state court did not have the authority to issue a writ of habeas corpus to a prisoner held in a federal prison. The Court reasoned that the writ of habeas corpus was a federal remedy, and that the state court did not have the authority to interfere with the federal government's power to imprison individuals. The Court also noted that the writ of habeas corpus was a remedy that could only be used to challenge the legality of a prisoner's detention, and not to challenge the conditions of the prisoner's confinement. The Court's decision in Betts v. Mugridge established that state courts do not have the authority to issue writs of habeas corpus to prisoners held in federal prisons. This decision has been cited in numerous subsequent cases, and has been used to support the principle that state courts do not have the authority to interfere with the federal government's power to imprison individuals.

In Betts v. Mugridge, the Supreme Court was tasked with deciding whether a state court had jurisdiction to hear an action brought by a non-resident against another non-resident in regards to property located within the state's borders. The majority opinion held that such jurisdiction did not exist and thus dismissed the case. In dissent, Justice Harlan argued that there should be no distinction between citizens of different states when it comes to access to justice in matters concerning real estate situated within a particular state's boundaries. He further asserted that if one party is allowed access then so too must all parties regardless of their residency status have equal opportunity for redress before any given court system as long as they are connected with some matter or controversy over which said court has authority under its laws and constitution. Thus, he concluded that since both parties were involved in this dispute regarding land situated within New York State then both should be able to bring suit before its courts without regard for either party’s residence status or citizenship rights elsewhere