Gunn v. Plant was a United States Supreme Court case that addressed the issue of whether a state court had the authority to issue a writ of mandamus to a federal court. The case involved a dispute between two parties, Gunn and Plant, over a contract for the sale of a steamboat. Plant had obtained a judgment against Gunn in a state court, and sought to enforce the judgment by obtaining a writ of mandamus from the state court to the federal court. The Supreme Court held that the state court did not have the authority to issue a writ of mandamus to a federal court, as the federal court was not subject to the jurisdiction of the state court. The Court further held that the state court could not issue a writ of mandamus to the federal court, as the federal court was not bound by the state court's judgment. The Court concluded that the state court lacked the authority to issue a writ of mandamus to the federal court, and that the writ of mandamus was therefore invalid. The Court's decision in Gunn v. Plant established that state courts do not have the authority to issue writs of mandamus to federal courts.

Justice Field delivered the dissenting opinion in Gunn v. Plant, arguing that the majority's decision was wrongfully based on a misinterpretation of state law. He argued that under California law, an individual who had been granted title to land by a Mexican grant could not be deprived of it without due process of law and compensation for any improvements made to the property. Furthermore, he asserted that Congress did not intend to interfere with such rights when they passed legislation concerning public lands in 1851 and 1852. Justice Field concluded his dissent by noting that if Congress had intended to deprive individuals like Gunn from their rightful titles then they would have done so explicitly rather than leaving it up to interpretation as they had done here.