Erie Railroad Co. V. Tompkins

Erie Railroad Co. v. Tompkins, 304 U.S. 64 (1938), is a landmark decision by the Supreme Court of the United States in which the Court held that federal courts did not have the judicial power to create general federal common law when hearing state law claims under diversity jurisdiction. In reaching this holding, the Court overturned almost a century of federal civil procedure case law, and established the foundation of what remains the modern law of diversity jurisdiction as it applies to United States federal courts.