This book presents research in an interdisciplinary field, resulting from the vigorous and fruitful cross-pollination between traditional deontic logic and computer science. AI researchers have used deontic logic as one of the tools in modelling legal reasoning. Computer scientists have discovered that computer systems (including their interaction with other computer systems and with human agents) can often be productively modelled as norm-governed. So, for example, deontic logic has been applied by computer scientists for specifying bureaucratic systems, access and security policies, and soft design or integrity constraints, and for modelling fault tolerance. In turn, computer scientists and AI researchers have also discovered (and made it clear to the rest of us) that various formal tools (e.g. nonmonotonic, temporal and dynamic logics) developed in computer science and artificial intelligence have interesting applications to traditional issues in deontic logic. This volume presents some of the best work done in this area, with the selection at once reflecting the general interdisciplinary (and international) character that this area of research has taken on, as well as reflecting the more specific recent inter-disciplinary developments between traditional deontic logic and computer science.