A natural Language based legal expert system for consultation and tutoring - The LEX project

Abstract

The LEX (Legal Expert System) project is one of the European based projects investigating legal expert systems from both a professional and a teaching perspective. The project is a cooperative project between the University of Tubingen and IBM Germany and developed out of research into a User Specialty Language system (USL) for natural language queries to a relational data base. The LEX system has as its main components a Natural Language Analyzer for analysis and logic representation of written texts. A Knowledge Base holding; sources from the legal codes, explanations from legal commentaries, some common sense knowledge, and a lexicon of approximately 20000 words. Finally a Deductive Component based upon tableau calculus, conducts inference within the system. The system has as its primary aim to enable lawyers to input in natural language a set of case facts and to ask questions on the juridical issues connected to those facts. Dialogue is controlled enabling intelligent explanation to the user when required. A secondary aim is to provide additional components so as to enable the system to tutor on the legal domain held within the system. The development of the system has enabled the project team to gain insights into the problem of formalization of legal rules within the German legal system.