Norms in Branching Space-Times -- Changing Legal Systems: Abrogation and Annulment Part I: Revision of Defeasible Theories -- Acting, Events and Actions -- A Tableaux System for Deontic Action Logic -- Information Security Economics - and Beyond -- Trust and Norms in the Context of Computer Security: A Logical Formalization -- Specifying Intrusion Detection and Reaction Policies: An Application of Deontic Logic -- Delegation of Control in Administrative Procedures -- Variations in Access Control Logic -- Reasoning about Conditions and Exceptions to Laws in Regulatory Conformance Checking -- Need to Know: Questions and the Paradox of Epistemic Obligation -- A Logical Analysis of the Interaction between 'Obligation-to-do' and 'Knowingly Doing' -- Reactive Kripke Models and Contrary to Duty Obligations -- Normative Consequence: The Problem of Keeping It Whilst Giving It up -- On the Strong Completeness of Åqvist's Dyadic Deontic Logic G -- Strata of Intervenient Concepts in Normative Systems -- A Deontic Logic for Socially Optimal Norms -- Praise, Blame, Obligation, and Beyond: Toward a Framework for Classical Supererogation and Kin -- Introducing Grades in Deontic Logics -- Pushing Anderson's Envelope: The Modal Logic of Ascription.

This volume presents the refereed proceedings of the 9th International Conference on Deontic Logic in Computer Science, DEON 2008, held in Luxembourg in July 2008. The 16 revised full papers presented together with 4 invited talks were carefully reviewed and selected for inclusion in the book. The topics addressed are development of formal systems of deontic logic and related areas of logic, and applications. Of particular interest is the interaction between computer systems and their users; the papers focus also on the special topic of logical approaches to deontic notions in computer science in the area of security and trust, encompassing applications in e-commerce as well as traditional areas of computer security.