This contribution explores the evolution of European criminal law through the prism of EU constitutional law and its experimental elements. The paper charts the history of European criminal law by reflecting on the question of to what degree criminal law as an EU policy stands out from the other corners of EU law policies. The paper examines to what extent use of EU law sources in the domain of criminal law has been used in an innovative way and how, as well as to what extent, it differs from mainstream EU law. Furthermore, the paper discusses the issue of enforcement and how the enterprise of EU criminal law could possibly be modernized from the perspective of fundamental rights protection. The paper concludes by looking at the incoming tide of legislative proposals in the area of EU criminal law and how it all adds up to an increased understanding of the AFSJ.