Separating world and regulation knowledge: where is the logic

Common sense knowledge plays a major role in legal reasoning, but should not be confounded with it. Reasoning about the world, and legal reasoning can be separated by assuming that a legal domain consists of an abstract model of a (social) system which is controlled by regulations. Regulations are applied to situation descriptions which are derived from the world model. Because more than one rule may be applicable, these legal consequences should be checked by applying legal metaknowledge. The separation enables more tractable, specialised inference mechanisms. Moreover it appears that in this way legal reasoning can be reduced to simple matching and conflict resolution at the meta-level without the usual problems about modal operators and nonmonoticity. These thesis has emerged from experimenting with validation of a new Dutch traffic regulation.