Following the dramatic events of 11 September 2001, the establishment of the European criminal area has seen an unprecedented acceleration. In this context, the Belgian Presidency of the European Union has obtained the agreement of the Council on three key instruments: the European arrest warrant, the common definition of terrorism and the establishment of Eurojust. Each represents a major step forward on the three main strands of work that the European Council assigned to the Council at its Tampere meeting: mutual recognition of judicial decisions in criminal matters, harmonisation of legislation and the establishment of European actors. The purpose of this book is to carry out an original reflection on these achievements. He also wondered about the challenges and prospects of criminal justice in the context of the Convention on the Future of the European Union, convened by the Heads of State or Government at the Laeken European Summit. The work carried out under the chairmanship of Mr Giscard d’Estaing provides an opportunity to reflect on the institutional reforms to be undertaken to make the European Union a genuine area of freedom, security and justice. Should the penal area be further deepened? Or, in other words, does mutual recognition predate the establishment of a ‘European criminal territory’? Is harmonisation of legislation a first step towards a European criminal law? Can Eurojust be seen as an anticipation of a European Public Prosecutor? The book is the result of the collaboration of an international team of academics and researchers, legal practitioners, national or European civil servants.