Eachus v. Broomall 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, Eachus, was held in a federal prison in Pennsylvania. Eachus 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 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 power to interfere with the federal government's authority 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 person's detention, and not to challenge the conditions of the detention. The Court's decision in Eachus v. Broomall 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 cannot interfere with the federal government's authority to imprison individuals.

In Eachus v. Broomall, the Supreme Court was tasked with determining whether a state court had jurisdiction to hear a case involving citizens of different states. The majority opinion held that the state court did not have such jurisdiction and thus reversed the judgment of the lower courts. Justice Field dissented from this decision, arguing that under Article III Section 2 of the Constitution, which grants federal courts original jurisdiction over cases between two or more states, Congress has authority to grant concurrent jurisdiction in certain circumstances to state courts as well. He argued further that since Congress had not specifically excluded suits between citizens of different states from its grant of concurrent jurisdictional power to state courts in 1875 (the year before this suit was brought), it should be assumed that they were included within it and therefore could be heard by both federal and state tribunals alike.