Federal common law

Federal common law is a term of United States law used to describe common law that is developed by the federal courts, instead of by the courts of the various states. Ever since Louis Brandeis, writing for the Supreme Court of the United States in Erie Railroad v. Tompkins (1938), overturned Joseph Story's decision in Swift v. Tyson, federal courts exercising diversity jurisdiction have applied state law as the substantive laws, with few exceptions.^[1] Nevertheless, there are several areas where federal common law continues to govern.