Abstract. One of the most salient tasks in law is legal assessment, and concerns the problem of determining whether some case is allowed or disallowed given an appropriate body of legal norms. In this paper we describe a system and Protégé 4 plugin, called OWL Judge, that uses standard OWL 2 DL reasoning for legal assessment. Norms are represented in terms of the LKIF Core ontology, as generic situation descriptions in which something (state, action) is deemed obliged, prohibited or permitted. We demonstrate the design patterns for defining the norms and actual cases. Furthermore we show how a DL classifier can be used to assess individual cases and automatically generate a lex specialis exception structure using OWL Judge. We illustrate our approach with a worked-out example of university library regulations