An ontology-based rule chaining algorithm for legal expert systems

In the field of law the most prominent tasks are legal assessment and qualification. These tasks aim at determining whether a legal case is allowed and which legal categories does it fulfil given an appropriate body of legal norms. We have developed a legal modelling framework called Emerald, which builds on Semantic Web standards and is able to solve these legal problems even providing means for information collection. Our proposed formal modelling approach of Emerald uses OWL 2 description logic combined with SWRL rules to answer legal qualification problems. In this paper we present an algorithm to collect input case specification from end users by conducting an interactive dialogue. A backward chaining algorithm generates relevant questions with respect to the qualification problem, taking into consideration any partial case description available and other constraints in description logic.