Mahn v. Harwood & Others 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 mandamus to a federal court. The case arose when the plaintiff, Mahn, sought to compel the defendants, Harwood and others, to appear in a state court and answer a complaint. The defendants argued that the state court lacked the authority to issue a writ of mandamus to a 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. The Court reasoned that the state court lacked the power to issue a writ of mandamus to a federal court because 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 a federal court because the federal court was not bound by the laws of the state. The Court's decision in Mahn v. Harwood & Others established that state courts do not have the authority to issue a writ of mandamus to a federal court. This decision has been cited in numerous cases since then, and it remains an important precedent in the area of federal-state relations.

Justice Field delivered the dissenting opinion in the case of Mahn v. Harwood & Others, arguing that a state court should not have jurisdiction over a foreign corporation when it is sued by an individual from another state. He argued that since corporations are creatures of the law and do not possess any physical presence within a particular state, they cannot be subject to suit in its courts unless authorized by Congress or through some other form of federal legislation. Furthermore, he contended that allowing states to exercise jurisdiction over foreign corporations would create conflicts between different states' laws and could lead to unfair outcomes for those involved in such suits. As such, Justice Field concluded that only Congress had authority to grant this power and thus held his dissent against granting jurisdiction over foreign corporations in this case.