There is no common law of the United States premised on a national customary law that the courts of the United States enforce as a national institution, in the interpretation of the constitution.
There is no federal general common law. Congress has no power to declare substantive rules of common law applicable in a State, whether they be local in their nature or 'general,' be they commercial law or a part of the law of torts. And no clause in the Constitution purports to confer such a power upon the federal courts. As stated by Mr. Justice Field when protesting in Baltimore & Ohio R. Co. v. Baugh, 149 U. S. 368, 149 U. S. 401, against ignoring the Ohio common law of fellow servant liability: 'I am aware that what has been termed the general law of the country -- which is often little less than what the judge advancing the doctrine thinks at the time should be the general law on a particular subject -- has been often advanced in judicial opinions of this court to control a conflicting law of a State. I admit that learned judges have fallen into the habit of ...