Ex parte Wilson 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 Wilson, was held in federal custody in the state of Missouri. Wilson sought a writ of habeas corpus from the state court, claiming that he was being held in violation of his constitutional rights. 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 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 the rights of its citizens. 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 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 the rights of its citizens.

In Ex Parte Wilson, the Supreme Court was asked to decide whether a federal court had jurisdiction over a case involving an alleged violation of state law. The majority opinion held that the federal court did not have jurisdiction in this matter and dismissed the case. Justice Field dissented from this decision, arguing that Congress had given district courts broad authority to hear cases arising under state laws when those cases involved issues of national importance or affected citizens of multiple states. He argued further that since this particular case involved questions about slavery and civil rights, it fell within Congress's intent for district courts to have such jurisdiction. Therefore, he concluded that the lower court should be allowed to proceed with hearing the case on its merits rather than dismissing it outright due to lack of jurisdiction.