Abstract: The text is based on the question that weather an arbitration tribunal can excite the constitutionality or not. The problem arises from the impossibility of infering that from the Italian law. It has been affirmed that the arbitrator has not the same competence and nature of action that the judge himself. From what derives that the arbitration cannot be considered as jurisdiction from the Member State. In fact, the arbitration jurisdiction is a kind of judicatory function, which comes from law application. This question has been debated both on jurisprudence and theory. The courts have decided that the arbitrator function is the same that the judges's in charge to find the best interpretation to the applicable law to the case. So, as the constitutionality analysis belongs to this process of interpretation, it is possible to conclude that the arbitrator is also competent to it. And this is near to the subject of finding the best solution towards parties will.