Bantz v. Frantz 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 Bantz, was held in a federal prison in Ohio. Bantz 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 Bantz v. Frantz 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.

Justice Field delivered the dissenting opinion in Bantz v. Frantz, arguing that the majority's decision was incorrect and should be reversed. He argued that under Missouri law, a contract between two parties could not be enforced if it had been made without consideration or with an illegal purpose. In this case, he believed there was no consideration for the agreement because both parties were already bound to each other by prior contracts which provided for all of their rights and obligations as tenants on the property in question. Furthermore, Justice Field argued that even if there had been some form of consideration given at one point during negotiations between them, it would have been rendered invalid due to its illegality since it involved a tenant attempting to purchase land from his landlord without proper authorization from either party’s respective legal representatives. Therefore, Justice Field concluded that since neither party received any benefit from their agreement and since such agreements are prohibited by state law anyway; then they should not be allowed to enforce said agreement against each other in court proceedings.