Matters of nationality remain within the exclusive competence of the Member States. They decide who can or cannot be an EU citizen. Being a national of a Member State is the condition sine qua non for acquiring EU citizenship, and therefore enjoying the rights linked to it. This led some scholars to the conclusion that EU citizenship might be characterised as a “derived condition of nationality”.

The ECJ interpreted the exclusive competence over nationality matters by Member States in the Micheletti case in 1992.

In this case, an individual with dual Argentinean and Italian nationality arrived in Spain wanting to exercise his right to freedom of establishment and to practice as an orthodontist. He was refused a residence permit by the Spanish authorities, because in such instances Spanish legislation refers to the last or effective residence, which in this case was Argentina. The ECJ ruled that nationality of one of the Member States was sufficient and that a citizen does not have to choose between the two nationalities. In fact, this judgment has dramatically influenced nationality law at the EU and national levels. The ECJ highlighted that this competence must be exercised in conformity with EC law. It also emphasized that another member of the Union that imposes additional conditions on the recognition of such a nationality in order to exercise the fundamental rights provided by the EC Treaty may not restrict the effects of nationality being attributed by one Member State.

Text of the ECJ judgment
Text of the AG opinion

Mrs. Carpenter was unable to benefit from a right to reside in the UK based on Directive 73/148, as the ECJ determined that the Directive only provided a right of residence for the spouses of Community nationals who moved from one Member State to another in order to provide services.

Mr. Carpenter was exercising his rights under Article 49 EC Treaty by selling services to nationals of other Member States and by occasionally traveling to other Member States. Nevertheless, the ECJ held that, within the context of the provision of services by Mr. Carpenter, EC law recognizes the right to family life. To deport Mrs. Carpenter, thereby causing a separation of the family, constituted:

“… An interference with the exercise by Mr. Carpenter of his right to respect for his family life within the meaning of Article 8 of the Convention for the Protection of Human Rights and Fundamental Freedoms, signed at Rome on 4 November 1950 (hereinafter “the Convention”), which is among the fundamental rights which, according to the Court’s settled case-law, restated by the Preamble to the Single European Act and by Article 6(2) EU, are protected in Community law”.

In other words, the ability to provide services would have been impaired if the spouse was deported due to the fact that she was responsible for the children when the husband was away on business. Therefore, the claim was that the deportation of the spouse could restrict the freedom to provide services of the husband and the Immigration Appeal Tribunal made a reference to the ECJ.

The ECJ ruled that a Member State may invoke a public interest ground to justify a national measure which is likely to restrict the freedom to provide services only if that measure is compatible with fundamental rights.

The fundamental right in question was the right to respect for family life protected under Article 8 ECHR and by the Community legal order and any interference with that right should be compatible with Article 8(2) ECHR and the principle of proportionality.

In conclusion, the restriction to the freedom to provide services that the Member State wanted to justify on the mandatory ground of public order, was disproportionate to the interference with the right to respect for family life.

Text of the ECJ judgment
Text of the AG opinion