Relationship between criminal and administrative enforcement and sanctioning for environmental crimes
Principle of legality (nullum crimen, nulla poena sine lege)
Principle of legality is protected by ECHR and, according to the CJEU, is one of the general principles of EU law. It precludes imposing sanction not recognised in the national law (see C-549/09 Arubis Bulgaria). To constitute a crime, it requires a clear and unambiguous legal basis (C-210/00, Käserei Champignon Hofmeister). This may present a difficulty if the national environmental law implements the EU law with its autonomous definitions.
For example, see the opinion of the General Advocate in C-624/17, Tronex, para 51:
As a general rule, in order to ascertain the meaning and scope of a provision, it is necessary to interpret the EU law by taking into account the wording of the provision and the objective pursued by the legislation in question (see C-184/14, A, para. 32, or C-304/15, Commission v United Kingdom) and also to examine its general scheme (see C-585/10, Møller, para. 28).