Phillips v. Moore 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 Phillips, was held in a federal prison in the state of Missouri. Phillips 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 Phillips v. Moore 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 person's detention, and not to challenge the conditions of the detention.

Justice Field delivered the dissenting opinion in Phillips v. Moore, arguing that the majority's decision was wrongfully decided and should be reversed. He argued that a contract between two parties is binding on both of them, regardless of any subsequent changes to state laws or regulations. In this case, he noted that there had been no change in the law since the contract was made; therefore it could not be used as an excuse for non-payment by either party. Furthermore, Justice Field argued that if one party were allowed to use such a defense against payment due under a contract then all contracts would become unenforceable and commerce would suffer greatly as a result. Finally, he concluded his dissent by noting that while courts have discretion when interpreting contracts they must also respect their terms and enforce them accordingly unless there has been some intervening change in law or regulation which affects its validity or performance