A methodology to create legal ontologies in a logic programming based web information retrieval system Jos´ e Saias and Paulo Quaresma Departamento de Inform´ atica, Universidade de ´ Evora, 7000 ´ Evora, Portugal jsaias|pq@di.uevora.pt May 21, 2004 Abstract. Web legal information retrieval systems need the capability to reason with the knowledge modeled by legal ontologies. Using this knowledge it is possible to represent and to make inferences about the semantic content of legal documents. In this paper a methodology for applying NLP techniques to automatically create a legal ontology is proposed. The ontology is defined in the OWL semantic web language and it is used in a logic programming framework, EVOLP+ISCO, to allow users to query the semantic content of the documents. ISCO allows an easy and efficient integration of declarative, object-oriented and constraint-based program- ming techniques with the capability to create connections with external databases. EVOLP is a dynamic logic programming framework allowing the definition of rules for actions and events. An application of the proposed methodology to the legal web information re- trieval system of the Portuguese Attorney General’s Office is described. Keywords: Ontologies, OWL, natural language processing, logic programming 1. Introduction Modern web legal information retrieval systems need the capability to represent and to reason with the knowledge modeled by legal on- tologies. In fact, the creation of ontologies allow the definition of class hierarchies, object properties, and relation rules, such as, transitivity or functionality. Using this knowledge it is possible to represent semantic objects, to associate them with legal documents, and to make inferences about them. OWL (Ontology Web Language) is a language proposed by the W3C consortium (http://www.w3.org) to be used in the ”semantic-web” en- vironment for the representation of ontologies. This language is based on the previous DAML+OIL (Darpa Agent Markup Language - (W3C, 2000)) language and it is defined using RDF (Resource Description Framework - (Lassila and Swick, 1999)). c  2004 Kluwer Academic Publishers. Printed in the Netherlands. ailaw_pq.tex; 28/05/2004; 20:11; p.1