Ex parte Medway 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 held in federal custody. The case arose when a prisoner, Medway, was held in federal custody in the state of Georgia. Medway sought a writ of habeas corpus from the state court, claiming that he was being held in violation of the Constitution. 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 federal custody. The Court reasoned that the writ of habeas corpus was a federal power, and that the state court did not have the authority to interfere with the federal government's power to detain prisoners. The Court also noted that the writ of habeas corpus was a fundamental right, and that the state court should not be allowed to interfere with the federal government's power to protect this right. In conclusion, 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 federal custody. The Court reasoned that the writ of habeas corpus was a federal power, and that the state court did not have the authority to interfere with the federal government's power to detain prisoners. The Court also noted that the writ of habeas corpus was a fundamental right, and that the state court should not be allowed to interfere with the federal government's power to protect this right.

In Ex Parte Medway, the Supreme Court was asked to decide whether a state court had jurisdiction over an action brought by a non-resident against another non-resident. The majority opinion held that the state court did not have such jurisdiction and dismissed the case. However, Justice Field dissented from this decision and argued that it should be up to each individual state to determine its own jurisdictional limits in cases involving non-residents. He noted that while some states may choose not to exercise their authority in certain circumstances, others may find it necessary or desirable for various reasons. Furthermore, he argued that if Congress has not specifically prohibited a particular form of jurisdiction then there is no reason why any one State should be prevented from exercising its power as it sees fit within its borders. In conclusion, Justice Field believed that since Congress had not explicitly forbidden this type of jurisdiction then each State should be allowed to make decisions about how far they will extend their reach into matters concerning out-of-state parties without interference from other States or federal courts.