In this Thematic Unit, students will explore the legal and institutional background of the process of harmonization of Criminal and Criminal Procedural Law in the European Union. Particular emphasis will be placed on the efforts to harmonise Criminal Law within the framework of the European Union, the historical development, the legal framework, the institutions, the principles of mutual assistance, co-operation and the approximation of national laws as well as the procedures and mechanisms that shape police and judicial cooperation in criminal matters within the framework of the Area of Freedom, Security and Justice. In this context, the principle of mutual recognition of decisions in criminal matters will be studied, in particular the European Arrest Warrant, cooperation between national prosecuting and judicial authorities, the rules on the acceptance of evidence and the rights of both accused persons and victims of crime, as well as the basic constitutive principles of Criminal Law governing all the aforementioned parameters.