Hunt v. Blackburn was a United States Supreme Court case that dealt with the issue of whether a state court had the authority to issue an injunction against a federal court. The case arose when the plaintiff, Hunt, sought to enjoin the defendant, Blackburn, from proceeding with a suit in a federal court. The state court granted the injunction, and the defendant appealed to the Supreme Court. The Supreme Court held that the state court did not have the authority to issue an injunction against a federal court. The Court reasoned that the state court was not a court of competent jurisdiction to issue such an injunction, and that the federal court had exclusive jurisdiction over the matter. Furthermore, the Court held that the state court's action was in violation of the Supremacy Clause of the United States Constitution. The Court's decision was significant because it established that state courts do not have the authority to interfere with the proceedings of a federal court. This decision has been cited in numerous subsequent cases, and it remains an important precedent in the area of federal court jurisdiction.

Justice Field delivered the dissenting opinion in Hunt v. Blackburn, arguing that the majority's decision was contrary to established precedent and would lead to a dangerous expansion of federal power. He argued that Congress had no authority under the Constitution to pass legislation regulating labor disputes between employers and employees, as it did with the Railway Labor Act of 1926. Furthermore, he noted that if such regulation were allowed then there would be nothing preventing Congress from passing laws governing any other type of contract dispute or even matters traditionally left up to state law. Justice Field concluded by stating his belief that allowing this kind of federal interference into contracts between private parties was not only unconstitutional but also detrimental to both liberty and justice for all citizens.