Several fundamental questions should be addressed when studying the relationship between the common constitutional traditions of Member States (CCTs) and national identities (NIS). First, the legal basis justifying the protec- tion of NIs against CCTs: this is not necessarily Article 4(2) TEU, which refers more to the constitutional structure of the State rather than to fundamental rights, but more likely the Preamble of the Charter of Fundamental Rights and, from another perspective, national constitutions. A second question investigates the similarities between NIs and sovereignty: albeit developed in different historical and political backgrounds, the two concepts may not be particularly distant from one another, particularly when they interact with the federal state. From another perspective, NIs can be defined not only as a barrier against CCTs, but also as a synonym of how the core of the national constitutional system is shaped and, in this latter option, the relationship with CCTs can imply a greater integration than in the first. Indeed, in the latter option, NIs can be seen as the bricks with which CCTs are built, so far as they are common, while they become a counterweight to CCTs when the NI of one Member State differs from the majority of the others. The final question examined concerns who is entitled to define a Member State s NI: the CJEU or the constitutional/supreme court of the Member State in question? Perhaps the CJEU s Taricco II decision will provide an answer to this query.