Reasoning by a Bipolar Argumentation Framework for PROLEG

We develop a system allowing lawyers and law school students to analyze court judgments. We describe a transformation from the logic programming language PROLEG to a bipolar argumentation framework (BAF) and the legal reasoning involved. Legal knowledge written in a PROLEG program is transformed into a BAF, in which the structure of argumentation in a judgment is clear. We describe two types of reasoning by the BAF: clarification of the entire structure and causality of arguments, and identification of the required evidence, and we show its applications on legal reasoning.