The principle of ne bis in idem as an individual right is textually guaranteed in Art. 50 CFR / Art. 54 CISA, on the one hand, and in Art. 4 Prot. No. 7 ECHR, on the other. The CJEU and the ECtHR have delineated many issues in their detailed case law and have reciprocally influenced each other’s jurisprudence. The article identifies three major problems: Firstly, the definition of “criminal proceeding” as a prerequisite for application of the principle relies on the Engel criteria identified by the ECtHR, but it is difficult to incorporate new forms of sanctions, such as “naming and shaming,” into this definition, and the fact that administrative sanctions do not fall within the ambit of ne bis in idem is not justifiably accounted for. Secondly, the courts may have determined which procedural acts meet the requirement of res judicata (terminating a criminal proceeding) and which ones do not. However, it is the Member State itself which determines whether a decision is final and whether national follow-up procedures are permitted, thus reinvigorating the issue of jurisdictional concentration. The author therefore proposes a solution relying foremost on bona fides, namely identifying to what extent the accused himself/herself was reasonably allowed to place trust in the finality of the proceeding. Thirdly, the normative nature of the process of identifying the precise act to which ne bis in idem applies proves problematic when legal entities are perpetrators, be it in characterising the legal interest protected or the identity of the criminal act itself. The author points to Art. 82 para. 1 TFEU, which provides a legal basis for a – potentially – convincing overall European approach to the concept of res judicata. The CJEU should only address problems of application of the principle of ne bis in idem in individual cases.