Ex parte Smith is 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, Smith, filed a petition for a writ of habeas corpus in a state court, claiming that he was being unlawfully detained in a federal prison. The state court granted the writ and ordered the federal prison to release Smith. The federal government appealed the decision to the Supreme Court, arguing that the state court did not have the authority to issue the writ. The Supreme Court held that the state court did not have the authority to issue the writ of habeas corpus. The Court reasoned that the writ of habeas corpus is a federal remedy and that the state court did not have the power to interfere with the federal government's authority to detain prisoners. The Court also noted that the writ of habeas corpus is a remedy that is available only to those who are being held in violation of federal law. Therefore, the state court did not have the authority to issue the writ in this case.

In Ex Parte Smith, the Supreme Court was asked to determine whether a state court had jurisdiction over an action brought by a non-resident against another non-resident. The majority opinion held that the state court did not have jurisdiction in this case because it lacked personal jurisdiction over either party. However, Justice Field dissented from this decision and argued that states should be allowed to exercise their power of judicial authority within their own borders regardless of where the parties reside. He reasoned that if states were denied such authority then they would become powerless when dealing with out-of-state litigants who could easily evade service or ignore judgments rendered against them due to lack of personal jurisdiction. Furthermore, he noted that allowing states to exercise such power would promote justice and protect citizens’ rights since individuals should not be able to escape liability simply by residing outside of a particular state's boundaries.