Erie R. Co. v Tompkins

A landmark case, overruling a doctrine theretofore followed for many years, and establishing the doctrine that, under the Federal Judiciary Act, except as to matters governed by the United States Constitution, Acts of Congress, or treaties, the law to be applied in any case in the federal court is the law of the state, and that the phrase "the laws of the several states" refers, not only to state law as enacted by the state legislature, but to the law of a state as declared by its highest court, whether the law thus declared is local in nature or is general, common, or commercial. The case is reported in 304 US 64, 82 L Ed 1188, 58 S Ct 817, 114 ALR 1487, and the case long cited as authority for the principle which was overruled is Swift v Tyson (US) 16 Pet 1, 10 L Ed 865.