Dr Ger Coffey, Associate Professor, School of Law, published a scholarly article entitled “Exceptions to the Ne Bis in Idem Principle in the Context of Articles 54 and 55(1)(b) CISA and Compatibility of Declarations Not to be Bound by that Principle with Articles 50 and 52(1) CFREU” in the New Journal of European Criminal Law. The judgment in Criminal proceedings against MR (Generalstaatsanwaltschaft Bamberg) Case C–365/21 was delivered on 23 March 2023 wherein the Court of Justice of the European Union (CJEU) examined the complex interrelated issues concerning Article 54 CISA interstate application of the ne bis in idem principle (in the context of free movement of persons), Article 55(1)(b) CISA exceptions to the application of that principle, Article 50 CFREU interstate application of the principle (in the context of a fundamental right), and Article 52(1) CFREU limitations to the application of that principle subject to the principle of proportionality. The CJEU examined the compatibility of declarations not to be bound by the application of Article 54 CISA commensurate with Article 55(1)(b) CISA in the context of a criminal organisation and financial crime, offences against national security or other equally essential interests, and the compatibility of such declarations with Article 50 and Article 52(1) CFREU. The CJEU ruled that Article 55(1)(b) CISA exception to the principle was compatible with Article 50 CFREU. This is the first CJEU judgment on exceptions to Article 54 CISA and compatibility of declarations not to be bound by that principle with Article 50 CFREU. This article examines the significance and implications of the judgment within the area of freedom, security and justice.