Abstracting security policy from, and transforming to, native representations of access check mechanisms

Abstracting access control policy from access check mechanisms allows for richer expression of policy, using a declarative model with semantics, than what is permitted by the access check mechanisms. Further, abstracting access control policy allows for uniform expression of policy across multiple access check mechanisms. Proof-like reasons for any access query are provided, such as who has access to what resource, built from the policy statements themselves, independent of the access check mechanism that provide access. Access is audited and policy-based reasons for access are provided based on the access control policy.