In Ex Parte George Milburn, the Supreme Court ruled that a state court had no jurisdiction to issue a writ of habeas corpus for an individual who was held in custody by federal authorities. The case arose when George Milburn, who had been arrested and detained by U.S. marshals on charges of violating federal laws, sought relief from the Maryland State Circuit Court through a petition for habeas corpus. The circuit court granted his request and issued the writ ordering his release from federal custody; however, this decision was overturned by the Supreme Court on appeal. In its ruling, the Supreme Court declared that only Congress could authorize such action against officers appointed under its authority and thus concluded that state courts lacked jurisdiction over matters involving individuals being held in federal custody pursuant to validly enacted statutes or regulations passed by Congress itself.

In Ex Parte George Milburn, 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 have jurisdiction and could proceed with its decision in this matter. However, Justice McLean dissented from this ruling on the grounds that it violated Article III Section 2 of the Constitution which grants exclusive federal judicial power over cases involving citizens from different states. He argued that since Congress has not yet passed any laws granting concurrent jurisdiction to state courts in such matters, they are unable to exercise their authority until such legislation is enacted by Congress. Furthermore, he noted that allowing individual states to make decisions regarding contracts between individuals from other states would lead to confusion and uncertainty as each state may interpret these contracts differently than others do. As such, Justice McLean concluded his dissent by asserting that only Congress can grant concurrent jurisdiction for disputes between citizens of different states and thus urged them to pass appropriate legislation so as not allow further violations of Article III Section 2 occur in similar cases going forward.