Remote rule execution

In a policy decision point (500) coupled to at least one remote attribute source (107a-c), a method of transforming an attribute-based access control (ABAC) policy (106) to facilitate evaluation includes: identifying a functional expression (F1) of the ABAC policy; forming, based on the sub-hierarchy of the policy that has F1 as its hierarch, a remote query intended for a RAS such that the output data from execution of the remote query correspond to the outcome of an evaluation of F1; and transforming the ABAC policy by replacing the sub-hierarchy by a second functional expression that represents the remote query. A method of evaluating an access request against an ABAC policy includes using such a transformed ABAC policy. Furthermore, a method of evaluating an access request against an ABAC policy includes identifying remotely executable sub-hierarchies and delegating these to remote attribute sources.