Mower v. Fletcher was a United States Supreme Court case that addressed the issue of whether a state court had the authority to issue a writ of habeas corpus to a prisoner held in federal custody. The case arose when the petitioner, Mower, was arrested and held in federal custody for violating the Neutrality Act of 1794. Mower sought a writ of habeas corpus from the state court, which the federal government argued was not authorized to issue such a writ. 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 federal custody. The Court reasoned that the writ of habeas corpus was a federal prerogative and that the state court did not have the power to interfere with the federal government's authority to detain a prisoner. The Court further held that the writ of habeas corpus was a federal remedy and that the state court could not interfere with the federal government's authority to enforce the Neutrality Act. The Court's decision in Mower v. Fletcher established that the state court did not have the authority to issue a writ of habeas corpus to a prisoner held in federal custody. The decision also established that the writ of habeas corpus was a federal prerogative and that the state court could not interfere with the federal government's authority to enforce the Neutrality Act.

Justice Field delivered the dissenting opinion in Mower v. Fletcher, arguing that the majority's decision was contrary to both precedent and sound legal reasoning. He argued that under prior decisions of this Court, a contract for personal services could not be enforced against an assignee unless it had been made with him or his predecessor in interest. In this case, there was no evidence that either party had ever agreed to any assignment of the contract; therefore, Justice Field concluded that neither party should have been held liable on it. Furthermore, he noted that even if such an agreement existed between them at one point in time, it would still be unenforceable because contracts for personal services are generally considered non-assignable due to their inherently personal nature. As such, Justice Field believed the lower court's ruling should have been affirmed instead of reversed by the majority opinion.