Access control in a distributed system with external users and various organizations is an important issue in systems' security. A comparative study between the existing models will help both: (1) researchers to propose new formalisms and models adapted to these requirements and (2) developers to choose the adequate ones for their applications. In this paper, we are interested in studying role based interoperability security policies. We propose to classify these models based on some criteria related to collaborative environment. Then, we discuss and detail the characteristics of each one. Finally, we propose some perspectives.