Ex parte French 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, William French, was held in federal custody in the state of California. French 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 prerogative, and that the state court did not have the power to interfere with the federal government's authority in this matter. 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 ability 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 prerogative, and that the state court did not have the power to interfere with the federal government's authority in this matter. 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 ability to protect this right.

In Ex Parte French, the United States Supreme Court was asked to determine whether a writ of habeas corpus should be issued in favor of an individual who had been arrested and detained by federal officials. The majority opinion held that the writ should not issue because it would interfere with Congress’s power to regulate interstate commerce. Justice Field dissented from this decision, arguing that the Constitution grants individuals certain rights which cannot be taken away without due process of law. He argued that since no such process had occurred in this case, issuing a writ of habeas corpus was appropriate and necessary for protecting these constitutional rights. Furthermore, he noted that while Congress has broad powers over interstate commerce, those powers do not extend so far as to allow them to deprive citizens of their fundamental liberties without providing any form or hearing whatsoever.