1. A system, comprising: an authorization redirector for receiving a request for an access control decision for a user, and for determining whether to use a predetermined authorization policy or a user role approximation of the predetermined authorization policy to process the request; and an adaptive authorizer for dynamically determining, at run-time, a user role approximation for the user responsive to the request, the user role approximation based on at least one of a system state and a system goal corresponding to a hierarchical inter-organizational model.