Arthur v. Stephani 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, Arthur, was held in a federal prison in the state of Missouri. Arthur 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. In conclusion, 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.

In the case of Arthur v. Stephani, the Supreme Court was tasked with determining whether a contract between two parties could be enforced despite one party's failure to comply with certain conditions in that contract. The majority opinion held that since both parties had agreed to those conditions, they were binding and enforceable. Justice Field dissented from this decision, arguing that while it is true that contracts should generally be upheld and enforced as written, there are exceptions when one party has failed to perform their obligations under the agreement or where performance would result in an injustice or hardship for either side. He argued further that if a court finds such circumstances present then it may modify or even set aside an otherwise valid contract so as not to cause harm or injustice for either side involved in the dispute.