This article proposes an explanation as to why institutional change – understood as more competences for the European Union's supranational institutions – has rarely led to policy change in the Area of Freedom, Security and Justice (AFSJ). It draws attention to the constraints that newly empowered actors have faced in the wake of introducing the co‐decision procedure. If the key principles of a given AFSJ sub‐policy – its ‘policy core’ – were defined before institutional change occurred, the Council (as the dominant actor of the early intergovernmental co‐operation) has found it easier to prevail in the altered structural environment and to co‐opt or sideline actors with competing rationales. The article compares the importance of the new decision‐making procedure with two alternative pathways potentially leading to policy change, namely, the power of litigation and the impact of unexpected external events.