Argumentation is defeasible when it is possible that conclusions are withdrawn in the light of further argumentation. This interdisciplinary study reports on current research in artificial intelligence, legal theory and argumentation theory. It is relevant for all interested in defeasible argumentation, legal reasoning and argument assistance software. The author combines theoretical reflection with illustrative examples and provides an overview of research into the design of argumentation software, which will be of interest both to researchers in the field of artificial intelligence and the law, and to legal practitioners.
