The SepaRope project aims to provide an understanding of how the different branches of government, from different levels of governance, co-determine each other’s powers within the EU. The project takes inspiration from Christoph Möllers’ conceptualisation of separation of powers derived from individual and collective self-determination as the central element of the justification of public authority. We build on this and aim to identify how the interactions between different branches within the EU contribute to or hinder democratic will-formation, and manage or fail to control the exercise of public power.