Abstract
We present the design, proof theory and metatheory of a logic for representing and reasoning about authorization policies. A salient feature of the logic, BL, is its support for system state in the form of interpreted predicates, upon which authorization policies often rely. In addition, BL includes Abadi et al.'s “says” connective and explicit time. BL is illustrated through a case study of policies for sharing sensitive information created in the US intelligence community. We discuss design choices in the interaction between state and other features of BL and validate BL's proof theory by proving standard metatheoretic properties like admissibility of cut.