The Belgian constitutional Court is inherently linked to federalism. On the one hand, this specialized Court created thirty years ago – and formerly known as the « Court of Arbitration », then limited to conflicts in competence, was specifically created because of the centrifugal nature of the Belgian federalism. Its evolution in jurisdiction illustrates a subtle parallelism with the successive state reforms. On the other hand, the Court’s composition is defined following a linguistic balance (between Dutch- and French-speakers), essential in Belgian institutions. The Court’s jurisprudence is subsequently getting increasingly salient in the jurisdictional and institutional frameworks both de jure and de facto, as its powers allow the constitutional Court to annul an unconstitutional law. Apart from its action regarding fundamental rights, the Court’s jurisprudence in respect of conflict in competence represents a remarkable example for the constant trade-off dynamic in intricate “communitarian” issues – and therefore underline the crucial role covered by the Court within the Belgian federal State.