In Ewing v. Howard, the Supreme Court of the United States was asked to decide 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, Ewing, was held in federal custody in the state of California. Ewing sought a writ of habeas corpus from the state court, which the court granted. The federal government then 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 prerogative, and that the state court did not have the authority to interfere with the federal government's power to detain a prisoner. The Court also noted that the writ of habeas corpus was a fundamental right, and that the federal government had the exclusive power to protect this right. The Court's decision in Ewing v. Howard established that the federal government had exclusive authority to issue writs of habeas corpus to prisoners held in federal custody. This decision has been cited in numerous subsequent cases, and has been used to support the federal government's authority to detain prisoners without interference from the states.

In Ewing v. Howard, the Supreme Court was tasked with determining whether a state court had jurisdiction to hear a case involving an alleged breach of contract between two citizens of different states. The majority opinion held that the state court did not have jurisdiction and that the matter should be heard in federal court instead. Justice Field dissented from this decision, arguing that it would be unfair for parties who are unable to access federal courts due to their financial situation or lack of knowledge about legal proceedings to be denied justice by having their cases dismissed without being heard on their merits. He argued further that Congress had never intended for such injustice when they passed laws allowing suits between citizens of different states in either state or federal courts, and thus he concluded that it was within the power of each individual state's judiciary system to decide which cases could properly come before them according to established rules and principles governing civil procedure.