This paper addresses issues involved in applying the event-condition-action (ECA) rule paradigm of active databases to policies-collections of general principles specifying the desired behavior of a system. We use a declarative policy description language, PDL, in which policies are formulated as sets of ECA rules. The main contribution of the paper is a framework for detecting action conflicts and finding resolutions for them. Conflicts are captured as violations of action constraints. The semantics of rules and conflict detection and resolution are defined axiomatically using logic programs. Given a policy and a set of action constraints, the framework defines a range of monitors that filter the output of the policy to satisfy the constraints.