A transnational ne bis in idem rule is a core element of the area of freedom, security and justice. It has been given different expressions in Article 50 of the Charter and Article 54 of the Convention Implementing the Schengen Convention (CISA). In its judgment of 27 May 2014, the Court dealt with the relation between these provisions. This article critically discusses the judgment’s reasoning and its conclusion that the “enforcement clause” (which subjects ne bis in idem to additional conditions regarding the enforcement of a penalty) is fully compatible with the Charter. It is submitted that additional elements should be taken into account in the necessity and proportionality test under Article 52(1) of the Charter, such as: a clarification of the right’s rationale, possible alternatives to the enforcement clause and a thorough balancing between security concerns, free movement, procedural fairness and material justice. The Court’s core argument, according to which the existing framework for judicial cooperation in criminal matters is insufficient to prevent risks of impunity is put under particular scrutiny. Furthermore, in the light of the previous case law on double jeopardy and the judgment in Case “M” of 5 June 2014, the article underlines the need to ensure consistency in the reasoning.
