French law after the 1789 revolution can be considered as an ideal type of ‘monism’. It retained a considerable legacy from the Ancien Régime concerning the political unification of the realm and the construction of a modern, relatively centralized state. However, the Ancien Régime had been based on a ‘corporate State’ which respected numerous privileges and a plurality of rules in the field of private law (customary laws, Roman law, canon law). The 1789 revolution dismantled this legal architecture and the French Assemblies built a new system based on the primacy of a unified statutory law. They were no more privileges and private law was secularized, the constitution of 1791 recognizing marriage as a purely civil contract. Between 1804 and 1810 the Napoleonic five codes achieved their scheme for a single law unifying civil, criminal and procedural matters. The law of March 21st 1804 introducing the Code civil des Français abrogated all rules of Roman law, customs or royal ordinances that were inconsistent with the Code. From the Napoleonic regime onwards, French law also developed the model of a very centralized and unified State, rejecting any idea of provincial or regional laws.