The EU plays an increasingly important role in issues such as the fight against organised crime and the management of migration flows, transforming the Area of Freedom, Security and Justice (AFSJ) into a priority of the EU's political and legislative agenda. This book investigates whether institutional change - the gradual communitarisation of the AFSJ - has triggered policy change, and in doing so, explores the nature and direction of this policy change. By analysing the role of the EU's institutions in a systematic, theory-informed and comparative way, it provides rich insights into the dynamics of EU decision-making in areas involving high stakes for human rights and civil liberties. Each chapter contains three sections examining: the degree of policy change in the different AFSJ fields, ranging from immigration and counter-terrorism to data protection the role of EU institutions in this process of change a case study determining the mechanisms of change. The book will be of interest to practitioners, students and scholars of European politics and law, EU policy-making, security and migration studies, as well as institutional change.