Erie Railroad Co. v. Tompkins

Erie Railroad Co. v. Tompkins is a 1938 decision of the Supreme Court of the United States that overruled Swift v. Tyson and fundamentally reshaped the relationship between federal and state law in diversity jurisdiction cases. The Court held that federal courts sitting in diversity jurisdiction must apply the substantive law of the state in which they sit, including state common law as declared by the state's own courts, rather than fashioning an independent federal general common law. Writing for the majority, Justice Louis Brandeis concluded that the prior practice announced in Swift v. Tyson was unconstitutional because it exceeded the powers granted to federal courts and produced unequal treatment of litigants depending on whether a case was brought in state or federal court. The case arose from a railroad injury lawsuit brought by Harry Tompkins after he was struck by an object protruding from a passing train while walking along a right-of-way in Pennsylvania. Erie Railroad Co. v. Tompkins remains one of the most cited decisions in American law and underlies the modern Erie doctrine governing choice of law in federal courts.