The fact that an order for reference concerning the interpretation of the Convention Implementing the Schengen Agreement, a convention adopted under Title VI of the EU Treaty in the version in force before the Treaty of Lisbon, does not mention Article 35 EU, but instead refers to Article 267 TFEU, cannot of itself mean that the Court does not have jurisdiction to answer the questions raised.

Furthermore, the fact that the decision terminating criminal proceedings is taken by the prosecuting authority and the fact that no penalty is enforced are not decisive for the purpose of ascertaining whether that decision definitively bars prosecution. First, Article 54 of the CISA is also applicable where an authority responsible for administering criminal justice in the national legal system concerned, such as the public prosecutor’s office, issues decisions definitively discontinuing criminal proceedings in a Member State, although such decisions are adopted without the involvement of a court and do not take the form of a judicial decision. As regards the absence of a penalty, it is only where a penalty has been imposed that Article 54 of the CISA lays down the condition that the penalty has been enforced, is actually in the process of being enforced or can no longer be enforced under the laws of the Contracting State of origin. The reference to a penalty cannot therefore be interpreted in such a way that the application of Article 54 of the CISA is — other than in a case in which a penalty has been imposed — subject to an additional condition.

For a person to be regarded as someone whose trial has been finally disposed of within the meaning of Article 54 of the Convention Implementing the Schengen Agreement (CISA), in relation to the acts which he is alleged to have committed, it is necessary, inter alia, that further prosecution has been definitively barred. That condition must be assessed on the basis of the law of the Contracting State in which the criminal-law decision in question has been taken. A decision which does not, under the law of the Contracting State which instituted criminal proceedings against a person, definitively bar further prosecution at national level cannot, in principle, constitute a procedural obstacle to the opening or continuation of criminal proceedings in respect of the same acts against that person in another Contracting State.

The principle of ne bis in idem laid down in Article 54 of the Convention Implementing the Schengen Agreement (CISA), read in the light of Article 50 of the Charter of Fundamental Rights of the European Union, must be interpreted as meaning that a decision of the public prosecutor terminating criminal proceedings and finally closing the investigation procedure against a person, albeit with the possibility of its being reopened or annulled, without any penalties having been imposed, cannot be characterised as a final decision for the purposes of those articles when it is clear from the statement of reasons for that decision that the procedure was closed without a detailed investigation having been carried out; in that regard, the fact that neither the victim nor a potential witness has been interviewed is an indication that no such investigation has taken place. That is the case where a decision has been adopted, without a more detailed investigation having been undertaken for the purpose of gathering and examining evidence, solely because the accused refused to give a statement and the victim and a hearsay witness were living in another Member State, so that it was not possible to interview them in the course of the investigation and was therefore not possible to verify statements made by the victim.

More specifically in that regard, whilst Article 54 of the CISA aims to ensure that a person, once he has been found guilty and served his sentence, or, as the case may be, been acquitted by a final judgment in a Contracting State, may travel within the Schengen area without fear of being prosecuted in another Contracting State for the same acts, it is not intended to protect a suspect from having to submit to investigations that may be undertaken successively, in respect of the same acts, in several Contracting States. Therefore, the interpretation of the final nature, for the purposes of Article 54 of the CISA, of a decision in criminal proceedings in a Member State must be undertaken in the light not only of the need to ensure the free movement of persons but also of the need to promote the prevention and combating of crime within the area of freedom, security and justice.

Moreover, the consequence of applying Article 54 of the CISA to such a decision would be to make it more difficult, indeed impossible, actually to penalise in the Member States concerned the unlawful conduct alleged against the accused.

Lastly, the application of Article 54 of the CISA to such a decision could undermine the mutual trust between the Member States. That mutual trust can prosper only if the second Contracting State is in a position to satisfy itself, on the basis of the documents provided by the first Contracting State, that the decision of the competent authorities of that first State does indeed constitute a final decision including a determination as to the merits of the case.

(see paras 45, 47-49, 52-54, operative part)