Upton v. McLaughlin was a United States Supreme Court case that dealt with the issue of whether a state court could issue a writ of habeas corpus to a prisoner who was being held in a federal prison. The case arose when a prisoner, Upton, was held in a federal prison in the state of New York. Upton sought a writ of habeas corpus from the state court, claiming that he was being held in violation of his constitutional rights. 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 remedy, and that the state court did not have the power to interfere with the federal government's authority to imprison individuals. The Court also noted that the writ of habeas corpus was a remedy that could only be used to challenge the legality of a prisoner's detention, and not to challenge the conditions of the prisoner's confinement. The Court's decision in Upton v. McLaughlin established that state courts do not have the authority to issue writs of habeas corpus to prisoners held in federal prisons. The decision also clarified the scope of the writ of habeas corpus, and established that it could only be used to challenge the legality of a prisoner's detention, and not to challenge the conditions of the prisoner's confinement.

Justice Field delivered the dissenting opinion in Upton v. McLaughlin, arguing that the majority's decision was wrongfully decided and should be reversed. He argued that a contract between two parties cannot be enforced if it is against public policy or violates an existing law. In this case, he believed that the contract violated both of these principles as it sought to limit competition by preventing one party from engaging in business with another company for a period of five years after their agreement had ended. Furthermore, Justice Field argued that such contracts are not only voidable but also illegal under state laws prohibiting monopolies and restraints on trade. He concluded his dissent by stating that while private agreements may sometimes be allowed to stand despite being contrary to public policy or violating existing laws, this particular agreement could not because its purpose was so clearly anti-competitive and unlawful.