In a Grand Chamber judgment of the Court of Justice of the European Union delivered on 5 September 2023 in Case C-689/21, X v Ministry of Immigration and Integration (Loss of Danish nationality), it ruled that nationality rules in Denmark that revoke national and Union citizenship, as presently constituted, infringes Article 20 TFEU and Article 7 CFR.
The nationality law in Denmark currently provides, inter alia, that a person born outside of Denmark, who possesses Danish citizenship through one or both of their parents, who has not formally resided in Denmark, shall cease to be a Danish citizen upon reaching the age of 22. The exception in this regard, where Danish citizenship can be retained, is when a person does not hold any other nationality. Before the age of 22, persons in such a situation can make an application to the state to ask for their Danish citizenship to be retained.
The referring national court in this case, the Eastern High Court of Denmark (Østre Landsret) asked whether Article 20 TFEU and Article 7 of the Charter of Fundamental Rights (CFR) preclude national law, as currently constituted, from revoking the nationality of a Member State (and thus, Union citizenship), where the proportionality of the consequences of that loss are not considered.
The CJEU began by reciting its usual description of Union citizenship as being ‘destined to be the fundamental status of nationals of the Member States’, and recounted that Member States must, when exercising their powers in the sphere of nationality, have due regard to EU law and, in particular, the principle of proportionality.
The Court then moved on to state that Member States may indeed. demand the expression of a ‘genuine link’ with a Member State. But, that said, consideration of a genuine link must accounted for ‘the consequences of that loss for the situation of the person concerned and, if relevant, for that of the members of his or her family, from the point of view of EU law’.
In other words, that ‘genuine link’ does not necessarily have to be to Denmark, but could be, by just of just one hypothetical example, be a Danish citizen, facing loss of their Danish nationality, by making use of their Danish nationality (and the Union citizenship it confers), for example, living in another EU Member State. The genuine link test, therefore, has to be wide.
The CJEU thus ruled that, in a situation such as that at issue in the main proceedings, in which the loss of the nationality of a Member State arises by operation of law at a given age and entails the loss of citizenship of the Union, the competent national (administrative) authorities and the national courts (and the CJEU) must be in a position to examine the consequences of the loss of that nationality and, where appropriate, to enable that person to retain his or her nationality or to recover it ex tunc.
The judgment of the CJEU in Case C-689/21, X v Ministry of Immigration and Integration (Loss of Danish nationality) is available here.

