## Facts

- Harry J. Tompkins, a Pennsylvania citizen, was struck by a passing Erie freight train while walking on a well-used path along Erie’s right-of-way in Pennsylvania, causing the loss of his right arm.
- Tompkins sued Erie Railroad Company, a New York corporation, in the U.S. District Court for the Southern District of New York under diversity jurisdiction.
- Pennsylvania decisional law treated a person in Tompkins’s position as a trespasser, limiting railroad liability to wanton or willful misconduct.
- The federal trial court applied a federal “general law” negligence standard (more favorable to Tompkins) rather than Pennsylvania law, and the jury returned a verdict for Tompkins.
- The Second Circuit affirmed the judgment for Tompkins.

## Issues

1. Whether a federal court sitting in diversity may apply an independent federal “general common law” rule, rather than the forum state’s substantive law, when no federal statute or constitutional provision controls.
2. Whether the Rules of Decision Act requires federal courts in diversity cases to apply state decisional law as well as state statutes.
3. Whether Swift v. Tyson’s approach permitting federal “general law” in diversity cases should be overruled.

## Decision

- The Supreme Court reversed the judgment for Tompkins and overruled Swift v. Tyson.
- The Court held that there is no federal general common law and that federal courts lack authority to displace state substantive law in diversity cases absent controlling federal law.
- The Court interpreted the Rules of Decision Act to require application of state law, including state common law as declared by the state’s highest court.
- Because the injury occurred in Pennsylvania and no controlling federal law applied, Pennsylvania substantive law governed Erie’s duty and potential liability.

## Legal Principles

- There is no federal general common law applicable in diversity cases.
- In diversity cases, except where governed by the U.S. Constitution or Acts of Congress, federal courts must apply the substantive law of the state, including state judicial decisions.
- The Rules of Decision Act’s reference to “laws of the several states” includes state decisional law, not only state statutes.
- Federal diversity adjudication should not permit different substantive outcomes based solely on choice of federal versus state forum, a disparity associated with forum shopping and unequal treatment of litigants.

## Conclusion

The Court required federal courts exercising diversity jurisdiction to apply state substantive law, including state common law announced by the state’s highest court, and rejected the prior practice of applying a federal “general law,” thereby aligning outcomes in federal and state court when no controlling federal law governs.


Erie R.R. Co. v. Tompkins, 304 U.S. 64 (1938)