Abstract
RBAC(Role Based Access Control) has the advantage that reflects the real world because it presents a basic access control model based on user's role in organizations or governments. But in RBAC model, the privileges of the senior roles in these hierarchies are inherited from those of the junior roles, so RBAC model has the privileges problem that he senior are given more privileges than they need. That is, it tends to infringe the Principle of Least Privilege. On the other hand, if we give some excessive constraints on the RBAC model without scrupulous care, it may be meaningless property of role hierarchies. Furthermore, such complicated constraints make it more difficult to mange resources and roles in huge enterprise environments. The purpose of this paper is to solve the problems of role hierarchies such as inefficient role managements and abuse of privileges by using newly presented the backward tag pointer path expression in the inheritance of privileges.