Tomlinson v. Branch 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, John Tomlinson, was held in a federal prison in the state of Georgia. Tomlinson sought a writ of habeas corpus from the state court, which was denied by the state court judge, Branch. Tomlinson then appealed 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 a federal prison. 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 imprison individuals. 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 this right. The Court's decision in Tomlinson v. Branch established that the state court did not have the authority to issue a writ of habeas corpus to a prisoner held in a federal prison. This decision has been cited in numerous subsequent cases, and has been used to support the idea that the federal government has the power to protect the fundamental right of habeas corpus.

In Tomlinson v. Branch, the Supreme Court was asked to decide whether a state court had jurisdiction over a case involving two 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, arguing that it violated Article III of the Constitution which grants exclusive federal judicial power in cases between citizens of different states. He argued that allowing state courts to exercise such authority would create an imbalance between federal and state powers and undermine Congress’s ability to regulate interstate commerce as well as its other enumerated powers under Article I of the Constitution. Furthermore, he noted that if each State were allowed to exercise such authority then there would be no uniformity in decisions regarding similar cases across jurisdictions; thus creating confusion for litigants who may not know where their rights are best protected or what laws apply when they cross into another State's territory.