Cassation is a legal procedure meant to make null and void a last instance ruling in violation of the law. Gradually accessible to ordinary appellants, the procedure is administered by the Conseil Privé in conformity with a regulation dating from June 28th 1738. Introduction and acknowledgement of the instance as well as the inquiry into the case and its decision are developed in this paper. Since a “clear and unambiguous” violation to the letter of the law was a prerequisite, successful appeals through such a cassation process tended to be fairly rare.