Enacted as § 34 of the Judiciary Act of 1789, the Rules of Decision Act makes state law the rule of decision in federal courts except where the Constitution, treaties, or federal statutes provide otherwise. It is the statutory root of Erie Railroad Co. v. Tompkins and the entire modern law of federal-court choice of law. Codified at 28 U.S.C. § 1652.
Rules of Decision Act
In forceCodified at28 U.S.C. § 1652
Enacted September 24, 1789 · ch. 20, § 34, 1 Stat. 92
Originally § 34 of the Judiciary Act of 1789.