This paper looks at the consequences of the social and political process of the Europeanisation of judicial power. The creation of arrest and judicial mechanisms at the European level represents an important aspect of European security, characterised by a multiplicity of political, social and judicial mobilisations, the most central instruments of which are the Eurojust Unit and the European Arrest Warrant (EAW). Drawn up and negotiated before 9/11, these two legal instruments were adopted in the name of the ‘global war on terror’ following the attacks on New York. The adoption of such political measures has important consequences for the legal form of these new mechanisms, the study of which allows us to explore the constitutional ramifications of counterterrorism policies in European democracies. We see that the European Union has modified its legal approach in the name of the fight against terror, in effect displacing and replacing the law at this level.