After five years from becoming fully operative, Regulation No 1/2003 reveals its potentialin terms of effectiveness. However, the shift towards an ex post, decentralised system of controlwas not accompanied by a ban on multiple prosecutions and parallel application of Union and National antitrust lawsis admitted. This article explores the potential violations of the principle of non bis in idem in the enforcement of Articles 101 and 102 TFEU considering the newly binding EU Charter of Fundamental Rights and the envisaged accession to the European Convention on Human Rights. The review carried out herein singles out five distinct scenarios and a number of deficiencies which may ultimately require amendments to the existing rules.