Collaborative Access Decisions: Why Has My Decision Not Been Enforced?

With the increasing popularity of collaborative systems like social networks, the risk of data misuse has become even more critical for users. As a consequence, there is a growing demand for solutions to properly protect data created and used within these systems. Enabling collaborative specification of permissions, while ensuring an appropriate levels of control to the different parties involved, inherently leads to decisions of some users being overruled by the policies of other users. Users need to be aware that this is happening and why, otherwise they may lose trust in the system, which can impact their willingness to collaborate. Enhancing user awareness requires that users know about and understand the conflicts that occurred. In this paper, we propose an approach to compute a justification for a decision in cases where conflicts occur and, based on this, generate feedback that explains users why their decision was not enforced.