Kompetenz-Kompetenz” principle [34] : the first one is related to the ability of the arbitrators to rule on their own jurisdiction, and the second, and more problematic one, is related to the fact that national courts can rule on the arbitral tribunal’s jurisdiction only after the arbitrators has done so. This second characteristic of the principle, however, is less accepted in national systems, and, as will be illustrated in details later, has given rise to several problems, especially in the U.S.