Roberts v. Ryer 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, John Roberts, was held in a federal prison in the state of New York. Roberts 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 Roberts v. Ryer 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 Roberts v. Ryer, the Supreme Court was asked to decide whether a contract between two parties that had been partially performed could be enforced by one of them in court. The majority opinion held that it could not, as the statute of frauds required all contracts for land sales to be in writing and signed by both parties. Justice Field dissented from this decision, arguing that since part of the contract had already been completed (the payment of money), there should have been an exception made so that at least some portion of it could still be enforced even if it did not meet all requirements under the statute of frauds. He argued further that such an interpretation would help protect innocent people who were taken advantage of due to their lack knowledge or understanding about legal matters like contracts and statutes.