In a judgment of 10 November 2016 the Court of Appeal in Brussels applied the non bis in idem principle in the context of an appeal against a decision of a national competition authority that imposed a fine for facts that had already been sanctioned by another national regulatory authority. The case concerned the lawfulness of the so-called ‘per sender model’ introduced by the incumbent Belgian postal operator bpost in 2010. In this context, the Court had to decide whether the application of the non bis in idem principle could be ruled out because general competition law and sector regulation aim to protect different legal interests. According to the Court, this was not the case. As a result, the Court annulled the decision of the competition authority because the ‘per sender model’ had already led to a judgement having force of res judicata. Given the far-reaching consequences of this finding, the judgment of the Court feeds the debate on having a more extensive cooperation between the national regulatory authorities in the Member States.