Beard v. Nichols 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 who was being held in a federal prison. The case arose when a prisoner, William Beard, was held in a federal prison in the state of Missouri. Beard 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 person's detention, and not to challenge the conditions of the detention. The Court's decision in Beard v. Nichols established that state courts do not have the authority to issue writs of habeas corpus to prisoners held in federal prisons. This decision has been cited in numerous subsequent cases, and has been used to support the principle that state courts cannot interfere with the federal government's authority to imprison individuals.

In Beard v. Nichols, the Supreme Court was asked to decide whether a contract between two parties that had been made in violation of an Indiana state statute was enforceable. The majority opinion held that the contract could not be enforced because it violated public policy and therefore should be void. Justice Field dissented from this decision, arguing that while contracts which violate statutes are generally unenforceable, there is no general rule stating such contracts must always be void; rather, each case should be decided on its own merits based on the facts presented and any applicable laws or regulations. He argued further that if a court finds a contract to have been made in good faith by both parties without knowledge of its illegality then it may still stand as valid despite being contrary to law.