Saulet v. Shepherd 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 held in a federal prison. The case arose when a Louisiana state court issued a writ of habeas corpus to a prisoner held in a federal prison in Louisiana. The federal government argued that the state court did not have the authority to issue the writ, as the federal government had exclusive jurisdiction over the prisoner. The Supreme Court held that the state court did not have the authority to issue the writ, as the federal government had exclusive jurisdiction over the prisoner. The Court reasoned that the writ of habeas corpus was a federal prerogative, and that the state court did not have the authority to interfere with the federal government's exclusive jurisdiction. The Court also noted that the writ of habeas corpus was a fundamental right, and that the federal government had the exclusive authority to protect that right. 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 prerogative, and that the state court did not have the authority to interfere with the federal government's exclusive jurisdiction.

In the case of Saulet v. Shepherd, Justice Field delivered a dissenting opinion arguing that the majority's decision was based on an incorrect interpretation of Louisiana law. He argued that under Louisiana law, when two persons are jointly liable for a debt and one pays it off in full without any contribution from the other person, then they should be released from their joint liability. The majority had held that this rule did not apply to cases where there is no express agreement between them regarding payment; however, Justice Field disagreed with this conclusion and argued that such an agreement should not be necessary for release from joint liability as long as both parties were aware of the payment made by one party. Furthermore, he noted that even if there was some ambiguity in state law regarding this issue, courts should interpret laws liberally so as to avoid injustice whenever possible. Therefore he concluded his dissent by stating his belief that both defendants ought to have been discharged from their obligation since only one had paid off all debts owed jointly by them both.