In Radford v. Folsom, the United States Supreme Court addressed the issue of whether a state court could enjoin a federal court from hearing a case. The case arose when the plaintiff, Radford, filed a suit in a federal court against the defendant, Folsom. Folsom then filed a motion in a state court to enjoin the federal court from hearing the case. The Supreme Court held that the state court did not have the authority to enjoin the federal court from hearing the case. The Court reasoned that the state court lacked jurisdiction to interfere with the proceedings of the federal court. The Court further held that the state court could not interfere with the federal court's jurisdiction to hear the case. The Court concluded that the state court's injunction was invalid and that the federal court had the authority to proceed with the case. The Court's decision established the principle that state courts cannot interfere with the proceedings of federal courts.

In Radford v. Folsom, the Supreme Court was tasked with determining whether a state court had jurisdiction to hear an appeal from a federal district court in which the appellant sought to set aside a judgment of foreclosure on his property. The majority opinion held that the state court did not have jurisdiction because it lacked authority over matters arising under federal law. Justice Field dissented, arguing that while Congress has exclusive power over cases involving federal laws and regulations, states are still allowed to exercise their own powers when dealing with such cases as long as they do not conflict with any congressional acts or decisions made by higher courts. He further argued that since there were no conflicting statutes or judicial precedents in this case, then the state court should be given jurisdiction and allowed to decide if the foreclosure judgment should be overturned or not.