Part 3 is dedicated to the analysis of the application of the legality principle in European criminal law and it is structured as follows. In this Chapter, the status quo of the principle of legality is examined. Its purpose is to identify the features of this principle in European criminal law and the lacunae and problems associated with it. In Chapter VII, the identified problems are examined from the general perspective of the European criminal justice system. The challenges legitimising such a system are analysed and a relational model of European criminal justice is proposed. In Chapter VIII, the principle of legality in European criminal law is revisited and reconstructed.

In this Chapter an inventory of the features of the legality principle in European criminal law is presented. The approach is similar to Chapter IV, as the aim is to observe the problems and lacunae of its application; in other words, the modus operandi of the principle of legality in EU law. The fragments of this principle in EU law are collected and mapped with reference to its different aspects in order to gain some perspective in a manner equivalent to the national legality principle. First, with regard to the lex scripta element, the sources of European criminal liability will be the focus, especially with respect to statutes and jurisprudence. In investigating lex praevia the focus is on its theoretical rationale, its application and specifically in curtailing the retroactivity of criminal liability. For lex certa the problem of predictability and accessibility of criminalisation is addressed. Finally, for lex stricta the question is whether there are any rules, principles or methods to guide judicial interpretation in European criminal law. Because the European criminal justice system functions at two levels, the application of these aspects is examined on both levels. As described below, the interaction of the European and national legal orders raises further questions regarding the distributive role of the legality principle and the obligation stemming from this principle for national and European authorities.

Furthermore, a problem-based approach is followed for each element in order to identify the problems, inconsistencies and lacunae associated with the legality principle.