Objective This seminar will explain the concept of ne bis in idem in criminal proceedings as currently defined by the EU and discuss its practical consequences for criminal law practitioners. Furthermore, the status quo regarding conflicts of jurisdiction in cross-border cases is presented and the practical consequences discussed. Key issues Same act, enforced penalty, composed penalties, judicial decisionsDefining the principle of ne bis in idem under Art. 54 of the Schengen Convention and Art. 50 of the Charter of Fundamental Rights of the EUThe recent case law of the Court of Justice of the EU: Spasic (C129/14 PPU); M. (C-398-12); etc.Ne bis in idem and prosecutorial independenceConflicts of jurisdictionIdentifying parallel investigations in the EUPositive and negative conflicts of jurisdictionPros and cons of the EU’s legal framework for conflicts of jurisdictionSpecial regulations for extradition, the European Arrest Warrant, and the European Investigation OrderTransfer of criminal proceedingsThe need for an initiative from the EU legislator