Lorings v. Marsh 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 Lorings, was held in a federal prison in Massachusetts. Lorings sought a writ of habeas corpus from the state court, claiming that he was being held in violation of the Constitution. 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 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 federal government had the exclusive power to protect this right. The Court's decision in Lorings v. Marsh established that the federal government had exclusive authority over the writ of habeas corpus, and that state courts could not interfere with the federal government's power to imprison individuals. This decision has been cited in numerous subsequent cases, and has been used to support the federal government's authority to imprison individuals without interference from the states.

In Loring v. Marsh, the Supreme Court was asked to decide whether a contract between two parties could be enforced even if it violated state law. The majority opinion held that such contracts were not enforceable because they contravened public policy and would undermine the authority of state legislatures to pass laws for their citizens' protection. However, Justice Field dissented from this decision on the grounds that enforcing these contracts did not necessarily violate public policy or interfere with legislative power since states had already passed statutes allowing individuals to enter into private agreements concerning matters which affected only them. He argued further that denying enforcement of such contracts would deprive individuals of their right to make decisions about their own affairs and thus infringe upon personal liberty as guaranteed by the Constitution's due process clause.