Legal reasoning with argumentation schemes

Legal reasoning typically requires a variety of argumentation schemes to be used together. A legal case may raise issues requiring argument from precedent cases, rules, policy goals, moral principles, jurisprudential doctrine, social values and evidence. We present an extensible software architecture which allows diverse computational models of argumentation schemes to be used together in an integrated way to construct and search for arguments. The architecture has been implemented in Carneades, a software library for building argumentation tools. The architecture is illustrated with models of schemes for argument from ontologies, rules, cases and testimonial evidence and compared to blackboard systems for hybrid reasoning.