Even a constitution with provisions interpreted as a limit to European integration that can never be exceeded, could be changed, in some countries by a constitutional amendment, in some others by the pouvoir constituant, i. e. in a way of constitutional uprising. However, any such a constitutional change has to respect some basic limits - a common core of all European national constitutions.
Such a ^common core" is a denominator shared by the constitutional provisions at both levels, national as well as European. Therefore, it is a proper linkage for multi-level constitutionalism, putting together constitutional foundations of Member States with fundamental values and principles governing the European Union itself.