The project addresses the relation between citizenship and the principle of mutual recognition in criminal matters. It seeks to explore if and how citizens are currently protected against arbitrary and discriminatory interferences of their rights and duties in the transnational Area of Freedom, Security and Justice. This project will analyze and map the state of the art of citizenship under mutual recognition instruments and, from thereon, aims to deliver a contribution to the concept and scope of citizenship in the area of criminal justice. In order to achieve this, it takes a comparative approach.