At least nine agencies can be counted operating as justice and home affairs (JHA) agencies.1 Among these, the ones that are more involved in the criminal justice dimension are Europol, the European Police College (CEPOL), the Judicial Cooperation Unit of the EU (Eurojust) and the proposed European Public Prosecutor’s Office (EPPO). This contribution aims to place and discuss the criminal justice agencies in the broad context of the constitutional architecture of the Area of Freedom, Security and Justice (AFSJ). For reasons of space, it focuses only on the judicial cooperation side, as opposed to police cooperation, thus it discusses Eurojust, and it incorporates some reflections on the possible establishment of the EPPO. The chapter considers two fundamental constitutional debates normally associated with the developments of the AFSJ:  the tension between intergovernmental cooperation (sovereign states deciding to cooperate transnationally, yet on the basis of national law) and supranational integration (entrusting supranational bodies with the task of addressing transnational phenomena, operating according to supranational EU law);2 and the tension between repression of crime and protection of fundamental rights.3 This chapter will

* The author is a PhD student at the Vrije Universiteit Brussels and at the Université Libre de Bruxelles. She would like to thank Angelo Marletta for his precious cooperation in the drafting of this chapter. She was also an intern at the legal service of Eurojust, and at the Italian Desk from October 2011 to March 2012. She would like to thank Laura Surano and Filippo Spiezia for their guidance during her internship.