Enterprises collect and use private information for various purposes. Access control can limit who can obtain such data. However, the purpose of their use is not clear. In this paper we focus on the purpose of data access and demonstrate that dynamic role-based access control (RBAC) mechanism is not sufficient for enforcement of privacy requirements. To achieve this we extend RBAC with monitoring capability and describe a formal approach to determining whether access control policies actually implement privacy requirements based on the behaviour of the system. We demonstrate the advantages of our approach using various examples and describe the prototype implementation of our technique.