Legal, social and computational knowledge are the building blocks of the information society. The emergence of the Internet, the availability of web-based services, the wide rangingimplications of the Semantic Web and the need to establish conventions that facilitate interactions among agents -human or electronic- are some of the issues lying behind the publication of this book. Trends in Legal Knowledge shows the results of the B-4 Workshop on Artificial Intelligence and Law held in Granada during the XXII World Congress of Philosophy of Law and Social Philosophy (IVR '05).