The absence of a single legal system, according to critics, is one of the three most important dimensions in which further European constitutionalization finds itself stymied. For critics, a constitutional polity must be founded with one common legal system. From this view, if the European Union has no common understanding of the rule of law, it is doomed. Concerns include (1) an unclear role for a Federal Court and its appellate powers, (2) a lack of uniform trans-European procedures for selection of justices, (3) a lack of clear rules for constitutional review, (4) indeterminate jurisdiction vis-à-vis the (Member) States and (5) the unresolved matter of ultimate legal authority itself (Kompetenz-Kompetenz).