European Union Citizenship: Rights, Status, and the Relationship With Nationality

European Union Citizenship: Rights, Status, and the Relationship With Nationality

1. Introduction

Citizenship of the European Union is one of the most distinctive features of the European legal order. It gives individuals a legal status that exists alongside their national citizenship and connects them directly to the institutions, rights, and constitutional principles of the Union. An EU citizen is not merely a national of a Member State who benefits indirectly from agreements between governments. Union citizenship creates an individual legal relationship between a person and the European Union, conferring rights that may be relied upon before national authorities and courts.

The concept was formally introduced by the Maastricht Treaty, which entered into force in 1993. Before that development, European integration had primarily been concerned with economic activity, particularly the movement of workers, services, goods, and capital. The legal position of individuals was therefore often connected to their participation in economic life. Union citizenship broadened this approach. It recognised individuals as participants in the European project not merely because they worked, traded, or provided services across national borders, but because they possessed the nationality of a Member State.

The central legal provision is Article 20 of the Treaty on the Functioning of the European Union (TFEU). It establishes that every person holding the nationality of a Member State is a citizen of the Union. It also makes clear that Union citizenship is additional to, and does not replace, national citizenship.

This relationship is fundamental. The European Union does not operate a separate naturalisation system through which individuals may independently apply for EU nationality. Instead, Union citizenship follows automatically from the possession of the nationality of a Member State. The rules governing the acquisition and loss of national citizenship remain primarily within the competence of individual Member States, although their exercise must respect EU law where it affects Union citizenship.

The legal framework is therefore built around two connected principles. First, Member States determine who their nationals are under their respective national laws. Secondly, because national nationality automatically determines access to Union citizenship, decisions concerning its acquisition or withdrawal may have consequences that fall within the scope of EU law.

The Court of Justice of the European Union (CJEU) has progressively developed this relationship. Its judgments have established that Union citizenship is the fundamental status of nationals of the Member States, while also recognising that the rights attached to that status are subject to the conditions and limitations established by the Treaties and secondary legislation.

2. The Legal Foundations of Union Citizenship

The principal legal provisions governing EU citizenship are found in the Treaty on European Union (TEU), the TFEU, and the Charter of Fundamental Rights of the European Union.

Article 9 TEU establishes the constitutional principle that every national of a Member State is a citizen of the Union. It also requires the Union to observe the principle of equality among its citizens, who must receive equal attention from its institutions, bodies, offices, and agencies.

Article 20 TFEU provides the operative definition. It establishes Union citizenship and identifies several rights associated with that status. These include the right to move and reside freely within the territory of the Member States, electoral rights in European Parliament and municipal elections, consular protection in third countries, and the right to petition the European Parliament and approach the European Ombudsman.

Articles 21 to 25 TFEU develop these rights further. They regulate free movement and residence, non-discrimination on grounds of nationality within the scope of the Treaties, electoral participation, consular protection, and certain participatory and administrative rights.

The Charter of Fundamental Rights reinforces this framework. Title V, entitled Citizens’ Rights, contains provisions on electoral rights, good administration, access to documents, the European Ombudsman, petitions, freedom of movement, and diplomatic and consular protection.

The relevant provisions include:

• Article 39: the right to vote and stand as a candidate in elections to the European Parliament.
• Article 40: the right to vote and stand as a candidate in municipal elections.
• Article 41: the right to good administration.
• Article 42: the right of access to documents.
• Article 43: the right to refer cases of maladministration to the European Ombudsman.
• Article 44: the right to petition the European Parliament.
• Article 45: freedom of movement and residence.
• Article 46: diplomatic and consular protection.

These provisions do not mean that every right in the Charter is reserved exclusively for EU citizens. Many fundamental rights apply to everyone within the jurisdiction of the Union or its Member States when EU law is being implemented. Citizenship rights form a distinct part of a wider fundamental-rights system.

Union citizenship must also be understood in the context of Article 2 TEU, which identifies the values on which the Union is founded, including human dignity, freedom, democracy, equality, the rule of law, and respect for human rights.

Together, these provisions establish citizenship as a constitutional status rather than merely an administrative label.

3. Nationality and Union Citizenship: The Fundamental Relationship

The relationship between national citizenship and Union citizenship is unusual. In most states, citizenship is a status created directly by domestic constitutional or statutory law. In the European Union, citizenship is established by EU law but depends entirely on the nationality of a Member State.

Article 20(1) TFEU provides that every person holding the nationality of a Member State is a citizen of the Union. It also expressly states that Union citizenship is additional to, and does not replace, national citizenship.

The consequence is straightforward: a person cannot acquire EU citizenship independently of the nationality of a Member State. A French, German, Bulgarian, Italian, or Polish national is automatically an EU citizen. Conversely, a national of a third country does not become an EU citizen merely by living, working, or studying in the Union.

Union citizenship is therefore derivative in its acquisition, but it has an autonomous legal significance once acquired. The rights it confers are governed by EU law and are not simply identical to the rights attached to national citizenship.

This distinction is important. A person may enjoy the rights of an EU citizen while living in a Member State other than the state of nationality. For example, a Bulgarian national who moves to Germany remains a Bulgarian citizen under Bulgarian law but also exercises rights under EU law, including free movement, residence, and participation in municipal and European Parliament elections in Germany, subject to the relevant legal conditions.

The Union does not create a single European nationality that replaces the national legal identities of its Member States. Instead, it establishes a common legal status that operates across national borders.

This arrangement also means that national citizenship laws have consequences beyond the territory and constitutional system of the state that adopts them. When a Member State grants nationality, the individual automatically acquires Union citizenship and the rights attached to it. When a person loses the nationality of their only Member State, that person ordinarily loses Union citizenship as well.

The consequences are not limited to the individual relationship between a state and its national. They affect the legal position of the person throughout the Union.

4. The Competence of Member States to Determine Nationality

The acquisition and loss of nationality remain primarily matters of national competence. Member States determine the conditions under which nationality may be acquired by birth, descent, naturalisation, marriage where national law provides for it, or other legally recognised procedures. They also establish the circumstances in which nationality may be lost, withdrawn, or renounced.

EU law does not establish a general European nationality code. Nor does it harmonise the substantive conditions for naturalisation across all Member States.

Nevertheless, national competence does not mean that nationality decisions are entirely outside the reach of EU law.

The CJEU has repeatedly held that Member States must exercise their powers concerning nationality with due regard to EU law whenever the consequences of a national decision affect the status and rights of Union citizens.

The principle was clearly established in Micheletti v Delegación del Gobierno en Cantabria (Case C-369/90). The Court held that a Member State must recognise the nationality granted by another Member State for the purposes of exercising rights under EU law. A host Member State cannot impose additional conditions designed to restrict the recognition of that nationality merely because the individual also possesses the nationality of a third country.

The judgment protects the uniform operation of Union citizenship. If every Member State could independently decide whether another Member State’s nationality should be recognised for EU purposes, the legal status of Union citizens would become uncertain and inconsistent.

The principle was developed further in Rottmann v Freistaat Bayern (Case C-135/08). The case concerned an individual who had acquired German nationality through naturalisation after previously holding Austrian nationality. Austrian nationality had been lost following the acquisition of German nationality. German authorities subsequently sought to withdraw the naturalisation because it had been obtained through deception. That withdrawal threatened to leave the individual stateless and without Union citizenship.

The Court accepted that Member States retain the power to determine the conditions for acquiring and losing nationality. However, it held that a decision capable of depriving an individual of Union citizenship falls within the scope of EU law and must be examined in the light of the principle of proportionality.

The national authorities must therefore consider whether the consequences of withdrawing nationality are proportionate to the legitimate objective pursued. In the circumstances of the case, the fact that naturalisation had been obtained through deception was relevant, but the consequences for Union citizenship could not simply be ignored.

The judgment did not remove national competence over nationality. It established that the exercise of that competence may be subject to EU-law review when it affects Union citizenship.

This principle was reaffirmed in Tjebbes and Others (Case C-221/17). The Court considered Dutch legislation under which nationality could be lost automatically after a prolonged period of residence outside the Netherlands and the European Union, subject to the statutory conditions. The loss of Dutch nationality also resulted in the loss of Union citizenship for individuals who held no other Member State nationality.

The Court accepted that Member States may adopt rules concerning the loss of nationality, including rules based on the absence of a genuine link with the state. However, where those rules also cause the loss of Union citizenship, the authorities must be able to examine the individual consequences and determine whether the loss is proportionate.

The assessment may need to consider the person’s private and family life, professional circumstances, residence, and the position of affected family members, particularly children.

The resulting principle is that national nationality laws remain within Member State competence, but their application cannot disregard the legal consequences created by EU citizenship.

5. The 2025 Judgment on Citizenship by Investment

A particularly important development occurred in Commission v Malta (Case C-181/23), decided by the Grand Chamber of the CJEU on 29 April 2025.

The case concerned Malta’s citizenship-by-investment scheme, under which naturalisation could be granted through a procedure based on predetermined financial contributions or investments.

The European Commission argued that the scheme violated EU law because it treated the grant of nationality, and therefore Union citizenship, as the result of a commercial transaction.

The Court held that Malta had failed to fulfil its obligations under Article 20 TFEU and Article 4(3) TEU by establishing and operating an institutionalised naturalisation scheme based on predetermined payments or investments.

The judgment is constitutionally significant because it addresses the external consequences of national decisions concerning nationality.

The Court acknowledged that Member States retain competence to determine the conditions for granting nationality. However, it emphasised that nationality creates a special relationship between the state and the individual, founded on solidarity, good faith, and reciprocity of rights and duties. Because nationality of a Member State automatically confers Union citizenship, the grant of nationality also produces consequences for the other Member States and the Union as a whole.

The Court concluded that a system in which nationality is granted in direct exchange for predetermined payments or investments, through a transactional procedure, is incompatible with the fundamental concept of Union citizenship.

The judgment should not be interpreted as preventing Member States from considering financial circumstances, investment, economic contribution, or other relevant factors in their national immigration and naturalisation policies. Its central concern was the institutionalised transactional nature of the scheme: nationality was effectively offered in exchange for a predetermined financial contribution rather than being granted through a genuine naturalisation process reflecting the special relationship between the state and the individual.

The decision demonstrates that the national competence to determine nationality is not unlimited where its exercise affects the constitutional structure of the Union.

It also reinforces the principle of sincere cooperation. The consequences of granting nationality are not confined to the issuing state because every Member State’s nationality carries the rights and status of Union citizenship.

6. The Fundamental Status of Union Citizenship

One of the most influential statements in EU citizenship law appears in Grzelczyk v Centre public d’aide sociale d’Ottignies-Louvain-la-Neuve (Case C-184/99).

The Court described Union citizenship as being destined to become the fundamental status of nationals of the Member States, enabling those who find themselves in the same situation to enjoy equal treatment irrespective of their nationality, subject to the relevant exceptions.

The judgment concerned a French student living in Belgium who sought access to a minimum subsistence allowance. The Belgian authorities questioned his entitlement because he was not Belgian and was not a worker.

The Court held that a Union citizen lawfully residing in another Member State could rely on the Treaty principle of non-discrimination, although the right was not unlimited and remained subject to applicable conditions.

The expression “fundamental status” has become central to the Court’s citizenship jurisprudence. It reflects the development of the European Union from a legal structure focused principally on economic integration into an order in which individuals enjoy rights by virtue of their status as citizens.

However, the expression must not be misunderstood. It does not mean that all EU citizens are entitled to identical treatment in every area of national law, regardless of circumstances. Nor does it eliminate the conditions imposed by the Treaties and secondary legislation.

The principle of equal treatment applies within the scope of EU law. It does not automatically bring every purely internal national situation within the competence of the Union.

The Court’s case law therefore combines an expansive constitutional understanding of citizenship with a recognition of the limits of EU competence.

7. Freedom of Movement and Residence

The right to move and reside freely within the territory of the Member States is among the most important rights attached to Union citizenship.

Article 21 TFEU grants every Union citizen the right to move and reside freely within the territory of the Member States, subject to the limitations and conditions laid down in the Treaties and measures adopted to implement them.

The principal legislative instrument is Directive 2004/38/EC, commonly known as the Citizens’ Rights Directive. It regulates the entry and residence rights of EU citizens and their family members when they move to or reside in a Member State other than the state of their nationality.

The Directive establishes different legal conditions depending on the duration and circumstances of residence.

For stays of up to three months, Article 6 generally allows EU citizens to reside in another Member State without conditions or formalities beyond holding a valid identity card or passport.

For residence exceeding three months, Article 7 provides different qualifying categories. These include:

• Workers and self-employed persons.
• Individuals who have sufficient resources not to become an unreasonable burden on the social assistance system of the host Member State and have comprehensive sickness insurance.
• Students who meet the relevant conditions, including sufficient resources and comprehensive sickness insurance.
• Family members accompanying or joining a qualifying Union citizen.

The Directive therefore does not create an unconditional right for every economically inactive citizen to reside indefinitely in another Member State while disregarding all financial and administrative requirements.

After five years of continuous legal residence, an EU citizen generally acquires a right of permanent residence under Article 16 of the Directive. This status is no longer subject to the conditions governing the initial period of residence, although it may be lost through an absence from the host Member State exceeding the period specified by the Directive.

The Directive also protects family members. A spouse, registered partner where the host state treats the partnership as equivalent to marriage, dependent children, and certain dependent relatives may derive residence rights under the applicable provisions. The rules also provide protection for certain other family members and partners whose circumstances require individual examination.

Importantly, family members do not need to be EU citizens themselves to benefit from the relevant derived rights.

In Baumbast and R v Secretary of State for the Home Department (Case C-413/99), the Court confirmed that Article 21 TFEU can have direct effect and that restrictions on residence must be assessed proportionately.

The case concerned a German national who had worked in the United Kingdom and whose family circumstances raised questions about continued residence. The Court recognised that the right of residence could not be restricted automatically without considering the individual’s circumstances and the proportionality of the measure.

Freedom of movement is therefore not merely a political aspiration. It is a legal right supported by Treaty provisions, secondary legislation, and judicial enforcement.

8. Non-Discrimination on Grounds of Nationality

Article 18 TFEU prohibits discrimination on grounds of nationality within the scope of application of the Treaties, without prejudice to any special provisions contained in them.

This principle is closely connected with Union citizenship. A citizen who moves to another Member State should not ordinarily be placed at a disadvantage solely because of their nationality when the relevant situation falls within EU law.

The prohibition is particularly important in relation to access to employment, education, social advantages, and certain public services.

In Grzelczyk, the Court applied the principle to a student who had lawfully exercised his right to reside in another Member State.

In Martínez Sala v Freistaat Bayern (Case C-85/96), the Court recognised that a Union citizen lawfully residing in a host Member State could rely on the Treaty prohibition of discrimination in circumstances falling within the scope of EU law, even though the individual was not economically active.

However, Article 18 does not establish a general prohibition of every difference in treatment between citizens of different Member States. The situation must fall within the scope of EU law, and the relevant legal framework may permit justified distinctions.

For example, certain social benefits may be subject to residence, employment, or resource conditions. The Citizens’ Rights Directive and the relevant social security legislation establish rules governing access to benefits and coordination between national systems.

In Dano v Jobcenter Leipzig (Case C-333/13), the Court considered the position of economically inactive EU citizens who did not satisfy the residence conditions under Directive 2004/38. It held that EU law did not require the host Member State to grant certain social assistance benefits where the applicants did not have a right of residence under the Directive.

The judgment illustrates the limits of the non-discrimination principle. Equal treatment is an important element of citizenship, but it operates within the legal conditions established by EU law.

9. Electoral Rights and Democratic Participation

Union citizenship gives individuals political rights that extend beyond the state of their nationality.

Article 22 TFEU provides that every Union citizen residing in a Member State of which they are not a national has the right to vote and stand as a candidate in municipal elections and elections to the European Parliament in the Member State of residence, under the same conditions as nationals of that state.

These rights are implemented through EU legislation, including Directive 94/80/EC on municipal elections and Directive 93/109/EC on elections to the European Parliament.

The right to vote in municipal elections recognises that individuals who live in a community and are affected by local decisions should be able to participate in its democratic processes, even if they are not nationals of the state concerned.

The right to participate in European Parliament elections is equally important. The European Parliament is the directly elected institution of the Union and represents EU citizens at the European level.

A Union citizen may generally vote in European Parliament elections either in the Member State of nationality or in the Member State of residence, subject to the relevant national procedures and safeguards against multiple voting. A person cannot vote more than once in the same European Parliament election.

The right to stand as a candidate is also recognised, subject to the eligibility conditions established by EU and national law.

The political rights of Union citizens do not extend automatically to national parliamentary elections. The right to vote in elections to a Member State’s national legislature remains principally governed by that state’s constitutional and electoral law.

Union citizenship therefore creates a form of transnational democratic participation without replacing the national democratic systems of the Member States.

10. The European Citizens’ Initiative

The European Citizens’ Initiative (ECI) provides a mechanism through which citizens may invite the European Commission to consider proposing EU legislation.

Its legal basis is Article 11(4) TEU, supplemented by Article 24 TFEU and Regulation (EU) 2019/788.

An initiative must be supported by at least one million eligible citizens from a significant number of Member States. It must also satisfy minimum support thresholds in at least one quarter of the Member States.

The organisers must register the initiative with the Commission before collecting statements of support. Registration is subject to legal requirements, including whether the proposed initiative falls within the Commission’s powers to submit a proposal for an EU legal act.

Once the required support has been collected and verified, the initiative is submitted to the Commission. The organisers are entitled to meet Commission representatives and present their proposal at a public hearing in the European Parliament.

The Commission must examine the initiative and provide a reasoned response explaining what action, if any, it intends to take. It is not legally required to introduce legislation simply because an initiative has achieved the necessary number of signatures.

The ECI is therefore a participatory democratic instrument rather than a direct legislative procedure. It allows citizens to place an issue on the European political and institutional agenda, but it does not transfer the Commission’s right of legislative initiative to private individuals.

Its constitutional significance lies in recognising that EU citizens can participate in shaping the Union’s legislative priorities beyond periodic elections.

11. Petitions and the European Ombudsman

Union citizenship also creates channels through which individuals may raise concerns about EU institutions and matters falling within the Union’s responsibilities.

Article 24 TFEU recognises the right to petition the European Parliament and the right to apply to the European Ombudsman. These rights are developed further in Articles 227 and 228 TFEU.

Under Article 227 TFEU, any Union citizen, and any natural or legal person residing or having a registered office in a Member State, may submit a petition to the European Parliament on a matter falling within the Union’s fields of activity that affects them directly.

The petition mechanism enables individuals to raise issues concerning the application of EU law, alleged violations of rights, or matters requiring institutional attention.

The European Parliament’s Committee on Petitions examines admissible petitions and may request information from the Commission or other relevant bodies. It may also organise hearings, request investigations, or draw attention to matters of concern.

The European Ombudsman performs a different function. Under Article 228 TFEU, the Ombudsman investigates instances of maladministration in the activities of EU institutions, bodies, offices, and agencies, subject to the Treaty framework.

Examples may include unreasonable administrative delays, failure to provide access to documents, procedural unfairness, or inadequate explanations of institutional decisions.

The Ombudsman cannot ordinarily investigate the activities of national, regional, or local administrations simply because they apply EU law. Complaints concerning national authorities may instead fall within the competence of national courts, national ombudsmen, or other supervisory bodies.

These mechanisms contribute to institutional accountability by giving individuals channels of communication and scrutiny beyond formal judicial proceedings.

12. Diplomatic and Consular Protection in Third Countries

Article 23 TFEU establishes the right of EU citizens to enjoy diplomatic and consular protection in the territory of a third country in which the Member State of their nationality is not represented.

An EU citizen who is travelling or residing outside the Union may therefore seek assistance from the embassy or consulate of another Member State if their own state has no accessible diplomatic or consular representation in that country.

The protection must be provided on the same conditions as those applicable to nationals of the assisting Member State.

This is particularly significant for citizens of smaller Member States whose diplomatic networks may not cover every country.

The right is implemented through Directive (EU) 2015/637, which establishes coordination and cooperation measures to facilitate consular protection for unrepresented EU citizens.

Consular assistance may include:

• Assistance in cases of arrest or detention.
• Support for victims of serious crime.
• Help following serious accidents or illness.
• Assistance in cases of death abroad.
• Support where travel documents have been lost or stolen.
• Assistance with emergency repatriation in appropriate circumstances.

The right does not mean that the European Union itself operates a single diplomatic service responsible for all EU citizens. The primary responsibility remains with the Member States. The legal framework ensures that an unrepresented citizen may obtain assistance from another Member State’s diplomatic or consular authorities.

The assisting state must coordinate with the Member State of nationality where appropriate, particularly in cases involving financial assistance, repatriation, or other significant measures.

This right demonstrates how Union citizenship can provide practical protection beyond the geographical territory of the European Union.

13. Access to EU Institutions, Documents, and Languages

Union citizenship also includes a series of rights concerning communication with and access to EU institutions.

Article 24 TFEU allows citizens to address the institutions and advisory bodies of the Union in one of the languages listed in Article 55(1) TEU and to receive a reply in the same language.

This right reflects the multilingual character of the Union and recognises that citizens should not be required to communicate with EU institutions exclusively in one or two dominant languages.

Article 15 TFEU and Article 42 of the Charter establish the right of access to documents of the European Parliament, the Council, and the Commission, subject to the applicable legal conditions and exceptions.

The principal implementing instrument is Regulation (EC) No 1049/2001 regarding public access to European Parliament, Council, and Commission documents.

Access to documents is important for transparency, democratic oversight, and public understanding of institutional decision-making. It enables individuals, journalists, researchers, civil society organisations, and other interested parties to examine documents held by the institutions.

The right is not unlimited. Exceptions may protect matters such as public security, international relations, privacy, commercial interests, legal proceedings, and the decision-making process, subject to the applicable legal tests.

The right to good administration under Article 41 of the Charter is also significant. It includes the right to have matters handled impartially, fairly, and within a reasonable time by EU institutions and bodies. It also encompasses the right to be heard before an individual measure adversely affecting a person is taken, access to relevant files subject to legitimate confidentiality interests, and the obligation of the administration to give reasons for its decisions.

Article 41 is addressed specifically to the institutions, bodies, offices, and agencies of the Union. Its principles should not automatically be treated as imposing the same provision directly on every national authority, although comparable procedural obligations may arise under other provisions of EU law and general principles.

14. The Scope and Limits of Union Citizenship: The Zambrano Principle

One of the most important developments in citizenship law concerns situations in which an EU citizen has not exercised the right to move to another Member State.

The general rule is that EU citizenship provisions apply where the situation falls within the scope of EU law. Historically, this often involved cross-border movement.

In Ruiz Zambrano v Office national de l’emploi (Case C-34/09), the Court developed an important qualification.

The case concerned Colombian parents of Belgian children who were Belgian nationals and therefore Union citizens. The children had not exercised their right to move to another Member State. The question was whether the parents could be refused residence and work rights in circumstances that would effectively force the children to leave the territory of the Union.

The Court held that Article 20 TFEU precludes national measures that have the effect of depriving Union citizens of the genuine enjoyment of the substance of the rights conferred by their status.

This became known as the Zambrano principle.

It does not establish a general right of residence for every third-country national who has a family relationship with an EU citizen. The protection is exceptional and depends on whether refusal of residence or another measure would, in practical terms, compel the Union citizen to leave the territory of the Union as a whole.

The Court has subsequently clarified the circumstances in which this principle applies. In cases involving children, the actual dependency relationship and the consequences of refusing residence to a parent may be decisive.

The judgment is constitutionally important because it recognises that Union citizenship can have legal consequences even in situations without conventional cross-border movement.

Nevertheless, the principle remains narrowly defined. A family relationship alone does not automatically create a derived right of residence under Article 20 TFEU.

15. Family Members Who Are Not EU Citizens

EU citizenship may also create residence rights for family members who are nationals of third countries.

The principal legal framework is Directive 2004/38/EC. Where an EU citizen moves to or resides in a Member State other than the state of their nationality, qualifying family members may accompany or join that citizen under the Directive, even if they do not themselves possess EU citizenship.

These rights are generally derived from the EU citizen’s right to move and reside freely. Their purpose is to ensure that the exercise of free movement is not made ineffective by preventing the citizen from maintaining family life in the host state.

The Directive distinguishes between core family members and other family members whose circumstances must receive particular consideration.

Core family members include a spouse, a registered partner where the host Member State treats the partnership as equivalent to marriage, direct descendants under the age of 21 or dependants, and dependent direct relatives in the ascending line. The precise application depends on the relevant provisions and the circumstances of the case.

For other family members, including certain dependent relatives and durable partners, Article 3(2) requires the host Member State to facilitate entry and residence in accordance with its national legislation and to undertake an extensive examination of personal circumstances.

The Court has also developed important principles concerning children who are EU citizens and their non-EU parents.

In Zhu and Chen (Case C-200/02), the Court considered the residence position of a young Irish citizen living in the United Kingdom with her Chinese mother. The judgment recognised that the child’s right of residence could require the recognition of a derived right for the parent who was the child’s primary carer, provided the relevant conditions were satisfied.

In Chavez-Vilchez and Others (Case C-133/15), the Court examined the circumstances in which a third-country national parent of a Union citizen child could derive a residence right under Article 20 TFEU. It emphasised the need for a genuine assessment of dependency and the consequences for the child if the parent were required to leave.

The distinction between rights under Directive 2004/38 and rights derived directly from Article 20 TFEU is essential. The Directive principally concerns movement to and residence in a Member State other than that of nationality, while Article 20 may apply in exceptional situations where the substance of Union citizenship would otherwise be undermined.

16. The Loss of Union Citizenship

Because Union citizenship depends on the nationality of a Member State, the loss of national nationality ordinarily results in the loss of Union citizenship.

However, the consequences of nationality withdrawal must be assessed in the light of EU law where the decision affects the status of a Union citizen.

The judgments in Rottmann and Tjebbes established that national authorities must consider proportionality when a decision or rule results in the loss of Union citizenship.

In Udlændinge- og Integrationsministeriet (Loss of Danish nationality) (Case C-689/21), decided on 5 September 2023, the Court examined Danish rules under which individuals could lose Danish nationality, and consequently Union citizenship, upon reaching a specified age if they had not maintained the required connection with Denmark and did not satisfy an applicable exception.

The Court confirmed that national rules on the loss of nationality must comply with EU law where they cause the loss of Union citizenship. The possibility of an individual examination and an effective procedure for restoring nationality may be necessary to ensure proportionality.

The Court’s approach recognises that loss of nationality can have consequences extending far beyond the domestic legal relationship between the person and the state.

A person may lose the right to reside and work in other Member States under EU law, the right to participate in European elections, and other rights connected with Union citizenship. Family members may also be affected.

This does not mean that Member States are prohibited from withdrawing nationality in every case. Fraudulent acquisition, prolonged absence, or other grounds recognised by national law may justify loss or withdrawal in appropriate circumstances.

The requirement is that the decision must be legally justified and proportionate, taking account of the individual consequences where EU citizenship is lost.

17. Rights and Responsibilities of Union Citizens

Article 20(2) TFEU refers not only to rights but also to duties of Union citizens. However, the Treaties do not establish a comprehensive and directly enforceable catalogue of personal duties comparable to the obligations that may arise under national citizenship law.

The practical content of Union citizenship is therefore predominantly expressed through rights.

EU citizens must nevertheless comply with applicable EU and national law when exercising their rights. For example, residence rights may depend on conditions concerning resources and sickness insurance; electoral participation is subject to applicable electoral procedures; and free movement may be restricted on grounds of public policy, public security, or public health under the relevant legal framework.

The Citizens’ Rights Directive requires restrictions on free movement to comply with proportionality and procedural safeguards. Measures based on public policy or public security must be based exclusively on the personal conduct of the individual concerned. Previous criminal convictions alone cannot automatically justify such measures.

The distinction between rights and duties is important. Union citizenship is not a complete substitute for national citizenship, and it does not create a general European system of compulsory civic obligations. It is a Treaty-based legal status whose principal function is to confer rights and establish a relationship of legal protection between individuals and the Union.

18. Judicial Protection of Union Citizenship Rights

Rights associated with Union citizenship are not merely political declarations. Many can be relied upon before national courts and administrative authorities, subject to their precise legal conditions and the relevant provisions of EU law.

The preliminary reference procedure under Article 267 TFEU is particularly important. National courts may refer questions concerning the interpretation of EU citizenship provisions to the CJEU. The Court provides an authoritative interpretation of EU law, while the national court resolves the underlying dispute.

The infringement procedure under Articles 258–260 TFEU also contributes to the protection of citizenship rights. The Commission may bring proceedings against a Member State where it considers that the state has failed to fulfil obligations under EU law.

Individuals may also challenge national measures before domestic courts and rely on directly effective provisions where the relevant conditions are satisfied. National courts must provide effective judicial protection for rights arising under EU law, in accordance with Article 19 TEU and Article 47 of the Charter where applicable.

The relationship between national courts and the CJEU is therefore essential. National courts are often the first institutions before which citizenship rights are asserted, while the CJEU ensures the consistent interpretation of the relevant EU legal framework.

The constitutional importance of Union citizenship is consequently reflected not only in the rights it confers, but also in the judicial mechanisms through which those rights are protected.

19. The Constitutional Significance of Union Citizenship

Union citizenship represents a major development in the constitutional structure of European integration.

It establishes a direct legal connection between individuals and the Union, independent of their participation in economic activity. It gives citizens rights to move and reside across national borders, participate in certain elections outside their state of nationality, seek consular protection, and engage with EU institutions.

It also creates limits on the exercise of national powers where those powers affect the status of Union citizenship.

The relationship between national and European citizenship is therefore neither one of complete independence nor one of complete substitution. National citizenship remains the legal gateway to Union citizenship, while EU law determines the consequences of that status within the European legal order.

The Court’s jurisprudence demonstrates the gradual constitutional development of this relationship. Grzelczyk established the fundamental-status principle. Micheletti protected the recognition of Member State nationality for EU purposes. Rottmann and Tjebbes subjected nationality decisions resulting in the loss of Union citizenship to proportionality review. Zambrano recognised that the substance of citizenship rights may require protection even in certain situations without conventional cross-border movement. Finally, Commission v Malta clarified that national competence over nationality must be exercised consistently with the constitutional principles underlying Union citizenship.

The result is a legal status that remains dependent on national nationality but cannot be treated as exclusively a matter of national concern.

20. Key Takeaways

• Article 20 TFEU establishes citizenship of the European Union.
• Every national of a Member State is automatically an EU citizen.
• Union citizenship is additional to, and does not replace, national citizenship.
• Member States retain primary competence over the acquisition and loss of nationality, but must exercise that competence consistently with EU law where Union citizenship is affected.
• Union citizenship is recognised by the CJEU as the fundamental status of nationals of the Member States.
• Article 21 TFEU and Directive 2004/38/EC govern the right to move and reside freely within the Union.
• Article 18 TFEU prohibits discrimination on grounds of nationality within the scope of EU law.
• Union citizens may vote and stand as candidates in municipal and European Parliament elections in their Member State of residence.
• The European Citizens’ Initiative provides a mechanism for citizens to invite the Commission to consider proposing legislation.
• EU citizens may petition the European Parliament and complain to the European Ombudsman.
• Unrepresented EU citizens may seek diplomatic and consular protection from another Member State in a third country.
• In Rottmann and Tjebbes, the Court established that decisions resulting in the loss of Union citizenship must satisfy proportionality requirements.
• In Zambrano, the Court protected the genuine enjoyment of the substance of Union citizenship rights in exceptional circumstances.
• In Commission v Malta (2025), the Court held that an institutionalised naturalisation scheme based on predetermined payments or investments was incompatible with EU law.

21. Frequently Asked Questions

1. What is citizenship of the European Union?

EU citizenship is a legal status established by Article 20 TFEU. Every person who holds the nationality of an EU Member State is automatically a citizen of the Union and enjoys the rights provided by the Treaties and applicable EU legislation.

2. Can a person become an EU citizen without holding the nationality of a Member State?

No. EU citizenship is acquired automatically through the nationality of a Member State. The European Union does not operate an independent naturalisation system through which a person may directly apply for Union citizenship.

3. Does EU citizenship replace national citizenship?

No. Article 20 TFEU expressly provides that Union citizenship is additional to, and does not replace, national citizenship. An individual retains their national citizenship while also enjoying the rights attached to Union citizenship.

4. Can a Member State withdraw the nationality of one of its citizens?

Member States retain the competence to determine the conditions for acquiring and losing nationality. However, where withdrawal results in the loss of Union citizenship, the decision must comply with EU law, including the principle of proportionality.

5. Can an EU citizen live permanently in another Member State?

Yes, subject to the applicable legal conditions. Under Directive 2004/38/EC, an EU citizen who has resided legally and continuously in another Member State for five years generally acquires a right of permanent residence.

6. Can an EU citizen receive social assistance in another Member State?

Potentially, but the right is subject to the applicable EU and national rules. Economically inactive citizens may need to satisfy residence conditions, including requirements concerning sufficient resources and sickness insurance. The principle of equal treatment does not remove all such conditions.

7. Can EU citizens vote in another Member State?

Yes. An EU citizen residing in a Member State of which they are not a national may vote and stand as a candidate in municipal elections and European Parliament elections in that state, subject to the applicable electoral rules.

8. Do family members who are not EU citizens have residence rights?

They may. Directive 2004/38/EC grants certain family members derived rights when they accompany or join an EU citizen exercising free movement rights. In exceptional circumstances, Article 20 TFEU may also require residence rights where refusal would deprive an EU citizen of the genuine enjoyment of the substance of their citizenship rights.

9. What is the significance of the Zambrano judgment?

In Ruiz Zambrano (C-34/09), the CJEU held that national measures cannot deprive EU citizens of the genuine enjoyment of the substance of the rights conferred by Union citizenship. The principle may protect third-country national family members where refusing them residence would effectively compel an EU citizen to leave the territory of the Union.

10. What happens if a person loses the nationality of their only EU Member State?

The person will ordinarily lose Union citizenship and the rights attached to it. However, where the loss results from a national decision or rule, the authorities must comply with EU law and, where required, examine whether the consequences are proportionate.

11. What is the European Citizens’ Initiative?

It is a participatory mechanism through which at least one million eligible citizens from a significant number of Member States may invite the European Commission to consider proposing legislation within its powers. The Commission must examine a valid initiative and provide a reasoned response, but it is not obliged to propose legislation.

12. What did the CJEU decide in Commission v Malta in 2025?

The Court held that Malta’s institutionalised citizenship-by-investment scheme, based on predetermined payments or investments in exchange for naturalisation, violated Article 20 TFEU and Article 4(3) TEU. The judgment confirmed that national competence over nationality must be exercised consistently with the fundamental principles of Union citizenship.

22. Conclusion

Citizenship of the European Union is a central element of the Union’s constitutional identity. It gives individuals a legal status that extends beyond their relationship with their state of nationality and enables them to exercise rights throughout the European legal order.

Its structure is based on a distinctive relationship between national and supranational law. Member States continue to determine the conditions under which their nationality is acquired and lost, but the consequences of those decisions may extend to the entire Union. Once national citizenship gives rise to Union citizenship, the rights attached to that status become protected by EU law.

The CJEU has developed this relationship through a series of important judgments, gradually clarifying the limits of national discretion and the practical content of Union citizenship. Its jurisprudence demonstrates that the status is neither a symbolic addition to national citizenship nor an unlimited source of rights. It is a legal institution governed by Treaty provisions, secondary legislation, fundamental rights, and principles of judicial protection.

The significance of Union citizenship lies precisely in this combination. It preserves the constitutional role of the Member States while recognising individuals as direct holders of rights within the European legal order. It is therefore one of the principal expressions of the Union’s development from an organisation of economic cooperation into a legal and political community of citizens.

23. Primary Legal Sources and Further Reading

Treaties and EU Legislation

1. Article 9 of the Treaty on European Union – establishes the relationship between Member State nationality and Union citizenship.
2. Article 20 TFEU – establishes citizenship of the Union and identifies its principal rights.
3. Articles 18–25 TFEU – Treaty provisions concerning non-discrimination, free movement, electoral rights, consular protection, and citizenship-related rights.
4. Directive 2004/38/EC – regulates the rights of EU citizens and their family members to move and reside freely within the Member States.
5. Directive 93/109/EC – establishes arrangements for the exercise of the right to vote and stand as a candidate in European Parliament elections.
6. Directive 94/80/EC – establishes arrangements for the exercise of electoral rights in municipal elections.
7. Regulation (EU) 2019/788 – governs the European Citizens’ Initiative.
8. Directive (EU) 2015/637 – establishes coordination and cooperation measures facilitating consular protection for unrepresented EU citizens in third countries.
9. Regulation (EC) No 1049/2001 – governs public access to European Parliament, Council, and Commission documents.
10. Charter of Fundamental Rights of the European Union – particularly Title V, concerning citizens’ rights.

Leading CJEU Judgments

1. Micheletti v Delegación del Gobierno en Cantabria, Case C-369/90 – recognition of Member State nationality for the purposes of EU law.
2. Grzelczyk v Centre public d’aide sociale d’Ottignies-Louvain-la-Neuve, Case C-184/99 – Union citizenship as the fundamental status of nationals of the Member States.
3. Baumbast and R v Secretary of State for the Home Department, Case C-413/99 – direct effect of the right of residence and proportionality.
4. Martínez Sala v Freistaat Bayern, Case C-85/96 – equal treatment and the position of a Union citizen lawfully residing in another Member State.
5. Rottmann v Freistaat Bayern, Case C-135/08 – withdrawal of naturalisation and the loss of Union citizenship.
6. Ruiz Zambrano v Office national de l’emploi, Case C-34/09 – protection of the genuine enjoyment of the substance of Union citizenship rights.
7. Dano v Jobcenter Leipzig, Case C-333/13 – residence conditions and access to social assistance.
8. Tjebbes and Others, Case C-221/17 – automatic loss of nationality and proportionality review.
9. Chavez-Vilchez and Others, Case C-133/15 – derived residence rights of third-country national parents of EU citizen children.
10. Udlændinge- og Integrationsministeriet (Loss of Danish nationality), Case C-689/21 – loss of national nationality and the requirement of proportionality.
11. Commission v Malta (Citizenship by investment), Case C-181/23 – the constitutional limits of national citizenship-by-investment schemes and the nature of Union citizenship.

Institutional Resources

• European Commission – EU Citizenship – overview of the rights and opportunities associated with Union citizenship.
• European Parliament – The Citizens of the Union and Their Rights – institutional explanation of the legal framework and political rights.
• Council of the European Union – Consular Protection – information about assistance available to unrepresented EU citizens in third countries.
• EUR-Lex – Citizenship of the Union – summary of the Treaty framework and principal rights.