The United States Supreme Court case, United Mine Workers of America v. Gibbs, 1965 revolved around the issue of federal jurisdiction over state law claims. The plaintiff, Gibbs, owned a coal mine in Tennessee and alleged that the United Mine Workers Union had conspired to force him out of business by encouraging his employees to strike and persuading other businesses not to work with him. He sued under both federal anti-trust laws and state tort law for interference with contractual relations. The question before the court was whether it could hear both claims or if it should remand the state claim back to a local court. In its decision, the Supreme Court held that when a district court has taken original jurisdiction over a federal claim then they also have discretion to hear all related claims arising from same nucleus of operative facts even if these additional claims would not be within their jurisdiction independently. This principle is known as "pendent jurisdiction". However, this power needs careful exercise considering judicial economy, convenience & fairness parties involved.

In the dissenting opinion for United Mine Workers of America v. Gibbs, Justice Hugo Black argued that federal courts should not have jurisdiction over state law claims simply because they are related to a federal question presented in the same case. He believed this expansion of power was unconstitutional and could lead to an imbalance between state and federal courts. Furthermore, he expressed concern that allowing such jurisdiction would open up opportunities for forum shopping by plaintiffs seeking more favorable outcomes in federal court. Justice Black also disagreed with the majority's view on "pendent" jurisdiction - where a federal court takes on additional state law claims due to their connection with a central federal claim - arguing it had no basis in statute or constitutionality.