This reference for a preliminary ruling raises for the first time the question of the extent of the discretion available to the Member States to determine who their nationals are. In so far as citizenship of the European Union, which depends, admittedly, on enjoyment of the status of national of a Member State, is established by the Treaty, can the powers of the Member States to lay down the conditions for the acquisition and loss of nationality still be exercised without any right of supervision for Community law? That is, in essence, the point at issue in this case. This case therefore calls for clarification of the relationship between the concepts of nationality of a Member State and of citizenship of the Union, a question which, it need hardly be emphasised, to a large extent determines the nature of the European Union.