Access control systems often use rule based frameworks to express access policies. These frameworks not only simplify the representation of policies, but also provide reasoning capabilities that can be used to verify the policies. In this work, we propose to use defeasible reasoning to simplify the specification of role-based access control policies and make them modular and more robust. We use the Flora-2 rule-based reasoner for representing a role-based access control policy. Our early experiments show that the wide range of features provided by Flora-2 greatly simplifies the task of building the requisite ontologies and the reasoning components for such access control systems.