In MEVS v. Conover, the United States Supreme Court was asked to decide whether a state court had the authority to issue a writ of habeas corpus to a prisoner who had been convicted in a federal court. The petitioner, MEVS, had been convicted in a federal court of a crime and was serving a sentence in a state prison. MEVS argued that the state court had the authority to issue a writ of habeas corpus to him, and that the writ should be granted. The Supreme Court held that the state court did not have the authority to issue a writ of habeas corpus to a prisoner convicted in a federal court. The Court reasoned that the writ of habeas corpus is a federal remedy, and that the state court did not have the power to grant the writ. The Court also noted that the writ of habeas corpus is a remedy for federal prisoners, and that the state court did not have the power to grant the writ to a prisoner convicted in a federal court. The Court concluded that the state court did not have the authority to issue a writ of habeas corpus to a prisoner convicted in a federal court. The Court held that the writ of habeas corpus is a federal remedy, and that the state court did not have the power to grant the writ.

In MEVS v. Conover, the Supreme Court was asked to decide whether a state court had jurisdiction over 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 because it lacked diversity among its parties and thus could not exercise federal judicial power under Article III of the Constitution. Justice Field dissented from this decision, arguing that while there may be no diversity in citizenship among the parties involved in this particular case, such lack should not prevent courts from exercising their authority when necessary for justice to prevail. He argued further that if Congress has granted certain powers to state courts then those powers must be respected and enforced by all other branches of government as well as by private individuals who are subject to them. Furthermore, he asserted that any attempt on behalf of either party or any branch of government to deny these rights would amount to usurpation and tyranny which cannot stand up against constitutional principles or public policy considerations.