Definition of Erie

v. Tompkins. The landmark case holding that in an action in the Federal court, except as to matters governed by the U.S. Constitution and Acts of Congress, the law to be applied in any case is the law of the State in which the Federal Court is situated. 304 U.S. 64, 58 S.Ct. 817, 82 L.Ed. 1188. This case overruled Swift v. Tyson, 41 U.S. 1, 16 Pet. 1, 10 L.Ed. 865, which held that there was a body of federal general common law to be applied in such cases.

That's the definition of Erie in Black's Law Dictionary 6th Edition. Courtesy of