Laber v. Cooper 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 a federal prison. The case arose when a prisoner, Laber, was held in a federal prison in the District of Columbia. Laber sought a writ of habeas corpus from the state court of Maryland, where he was originally convicted, in order to challenge his conviction. 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 a federal prison. The Court reasoned that the power to issue writs of habeas corpus was a federal power, and that the state court did not have the authority to interfere with the federal government's power to imprison individuals. The Court also noted that the state court could not interfere with the federal government's power to enforce its laws. The decision in Laber v. Cooper established that state courts do not have the authority to issue writs of habeas corpus to prisoners held in federal prisons.

In Laber v. Cooper, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving citizens of different states. The majority opinion held that the state court did have jurisdiction and could hear the case. However, Justice Field dissented from this decision on two grounds: first, he argued that under Article III of the Constitution, only federal courts can exercise judicial power in cases between citizens of different states; second, he contended that Congress has not given any authority to state courts to do so either directly or by implication. He concluded by stating his belief that allowing such suits in state courts would be an unconstitutional extension of their powers and would lead to confusion and conflict among both federal and state jurisdictions.