Priority rules are often considered to be a promising method how to reduce number of maneuvering aircraft in the envisioned new (distributed) ATM separation modes. In the presented paper, we discuss priority rules that have been so far used, developed and suggested for the autonomous aircraft concept. The objective is to consider their advantages and drawbacks as well as factors that should be reflected in the definition of such rules for self separation operations in the future ATM. The relation between the priority rules on one side and applied conflict resolution strategy and information sharing process on the other side is also described. The paper concludes by a suggestion how to overcome the drawbacks of the existing priority rules through a combination of several operational elements.