Neither at the international nor at the European level there are binding instruments setting up a mechanism to prevent and resolve conflicts of exercising jurisdiction in criminal matters, i.e. those situations in which two or more states claim jurisdiction over the same facts and parallel criminal proceedings have been therefore initiated. Even in the EU, the principle of ne bis in idem – developed by the Court of Justice of the European Union – can intervene only at an advanced stage of the proceeding and it is applied on the basis of the “first come, first served” rule. However, it does not say anything on who should prosecute an offender in the European territory.With the entry into force of the Lisbon Treaty, there are new legal basis to regulate jurisdiction conflicts in criminal matters. By striving for a common European judicial space based on mutual trust and European citizenship where rights and obligations can be enforced by EU bodies and agencies, the exercise of criminal jurisdiction cannot be defined only on the basis of the prerogatives of sovereign nation states.This project aims at elaborating a new legal framework for the prevention and resolution of conflicts of jurisdictions in criminal matters in the Area of Freedom, Security and Justice. In particular, it aims at producing a set of recommendation for the EU institutions on how to make use of the existing legal basis. These recommendations will be elaborated within an international working group composed of academics and practitioners. The comparison with instruments adopted at the EU level in the international private law field represents one of the most innovative aspects of the project’s methodology. For this reason, the Working Group will be composed also of experts in the private law domain in order to analyse the possibilities and limits of the applicability to the criminal law field of criteria elaborated in international private law.