Deontic logic originated from moral philosophy and the philosophy of law as an attempt to formalise normative and legal reasoning. This book draws on the experience of researchers - working in fields as diverse as Artificial Intelligence, linguistics, computer system specification and law - who have discovered the benefits of deontic logic when applied to solving computer science and AI problems. A useful logic in which to specify normative system behaviour, deontic logic has a broad spectrum of possible applications within the field: from legal expert systems to natural language processing, database integrity to electronic contracting and the specification of fault-tolerant software. This book provides a unique and timely assessment of the practical value of deontic logic for computer scientists in AI and law and, more particularly, in such areas as distributed AI and intelligent cooperative information systems.