Dual Nationality

Dual Nationality refers to the legal status in which a person simultaneously possesses the nationality of two States. It arises when the nationality laws of two States operate in such a way that the same individual is recognised as a national by both States.

Dual nationality is an important issue in International Law because it may create questions concerning diplomatic protection, jurisdiction, military obligations, taxation, extradition and allegiance.

Meaning

A person has dual nationality when two States legally recognise that person as their national.

For example:

State A → recognises X as its national

State B → also recognises X as its national

Therefore:

X → National of State A + National of State B

Dual nationality may arise automatically or through a person’s voluntary acquisition of another nationality.

How Dual Nationality Arises

Dual nationality commonly results from differences between national laws.

The principal situations include:

• jus soli and jus sanguinis operating together;
• naturalisation;
• marriage;
• adoption;
• State succession;
• acquisition of nationality without automatic loss of previous nationality.

Dual Nationality by Birth

A person may acquire two nationalities automatically at birth.

For example:

Child born in State A

↓

State A applies jus soli

↓

Child acquires State A nationality

At the same time:

Parents are nationals of State B

↓

State B applies jus sanguinis

↓

Child acquires State B nationality

The child therefore possesses both nationalities.

Dual Nationality Through Naturalisation

A person may acquire the nationality of a second State through naturalisation while retaining their original nationality.

Whether this happens depends upon the laws of both States.

For example:

Original nationality → State A

↓

Naturalisation → State B

↓

State A permits retention

↓

State B grants nationality

↓

Dual nationality

Dual Nationality Through Marriage

Marriage can sometimes facilitate acquisition of another nationality.

However, modern nationality law generally does not automatically make a person a national of their spouse’s State merely because of marriage.

Where nationality is acquired through marriage, dual nationality may arise if the original nationality is retained.

Dual Nationality Through Adoption

A child may acquire the nationality of adoptive parents while retaining another nationality, depending upon the laws of the States concerned.

Dual Nationality and State Succession

State succession can also create dual nationality problems.

When States:

• merge;
• divide;
• dissolve;
• transfer territory;

individuals may potentially acquire the nationality of a successor State while retaining another nationality, depending upon the applicable rules.

Is Dual Nationality Permitted by International Law?

International Law does not generally prohibit dual nationality.

Whether a person can possess two nationalities is primarily determined by the domestic laws of the States concerned.

One State may permit dual nationality while another may require a person to renounce their previous nationality upon naturalisation.

Therefore:

International Law → does not universally prohibit dual nationality

Domestic law → determines whether dual nationality is recognised

Effective Nationality

When a person possesses more than one nationality, International Law may sometimes need to determine which nationality is effective or genuine.

Relevant factors may include:

• habitual residence;
• family connections;
• centre of interests;
• social ties;
• participation in public life;
• actual attachment to a State.

The concept becomes particularly important in international disputes involving diplomatic protection.

Nottebohm Case

In Nottebohm (Liechtenstein v. Guatemala), 1955, the ICJ considered the international effect of nationality.

The case involved Friedrich Nottebohm, who had strong connections with Germany but acquired Liechtenstein nationality.

The ICJ examined the connection between Nottebohm and Liechtenstein and concluded that Liechtenstein could not rely upon that nationality against Guatemala for purposes of diplomatic protection in the circumstances of the case.

The case is therefore important in discussions of:

• genuine nationality;
• effective nationality;
• diplomatic protection.

However, Nottebohm should not be understood as establishing a universal rule that every nationality must always satisfy a “genuine connection” test.

Dual Nationality and Diplomatic Protection

Dual nationality creates special problems in diplomatic protection.

Suppose:

Person X → national of State A + State B

X suffers injury in State C

Both State A and State B may potentially have nationality connections with X.

Questions may arise concerning:

• which State can exercise diplomatic protection;
• whether State A can protect X against State B;
• whether State B can protect X against State A;
• which nationality is considered effective.

Diplomatic Protection Against a State of Which the Person Is Also a National

Traditionally, International Law placed significant restrictions on a State exercising diplomatic protection against another State of which the injured person was also a national.

The modern position is reflected in the ILC Draft Articles on Diplomatic Protection, 2006.

Where a person is a national of both the protecting State and the respondent State, diplomatic protection is generally restricted unless the nationality of the protecting State is predominant, both at the date of injury and the date of the official presentation of the claim.

Mergé Claim

The Mergé Claim (1955) is an important authority concerning dual nationality and diplomatic protection.

The case involved a person who possessed both Italian and American nationality.

It is traditionally associated with the principle that a State generally cannot exercise diplomatic protection against another State of which the injured person is also a national.

The case is important in understanding the non-responsibility or non-protection principle in dual nationality cases.

Nationality of the Respondent State

The problem becomes particularly significant where:

Person → National of State A + State B

State A → seeks diplomatic protection

State B → is the State accused of the internationally wrongful act

The person’s dual nationality creates a conflict between:

• the nationality of the protecting State;
• the nationality of the respondent State.

Modern International Law addresses this through rules concerning predominant nationality.

ILC Draft Articles on Diplomatic Protection

The International Law Commission’s Draft Articles on Diplomatic Protection, 2006 provide important rules concerning dual nationality.

They recognise that a State may exercise diplomatic protection in relation to a dual national in specified circumstances.

The rules seek to determine whether the nationality of the protecting State is predominant in relation to the nationality of the respondent State.

Dual Nationality and Jurisdiction

Dual nationality may give two States a basis for exercising jurisdiction over the same person.

For example:

State A → nationality jurisdiction

State B → nationality jurisdiction

If the person commits an offence abroad, both States may potentially claim jurisdiction under their domestic laws.

This can create conflicts concerning:

• criminal prosecution;
• extradition;
• punishment;
• military obligations.

Active Nationality Principle

Under the active nationality principle, a State may exercise jurisdiction over its nationals for certain conduct committed outside its territory.

A dual national may therefore potentially fall within the jurisdiction of both States of nationality.

Passive Personality and Dual Nationals

Dual nationality can also complicate jurisdiction based upon the nationality of the victim.

Different nationality principles may overlap when:

• the accused has two nationalities;
• the victim has another nationality;
• the offence occurs in a third State.

Dual Nationality and Extradition

Dual nationality can create complicated extradition questions.

A person may be:

National of State A

and

National of State B

If State C requests extradition, the States of nationality may have different rules concerning:

• extradition;
• prosecution;
• refusal to extradite nationals;
• transfer of proceedings.

Dual Nationality and Military Service

A dual national may potentially be subject to military obligations in both States.

Domestic law and applicable international agreements may determine how conflicting obligations are resolved.

Dual Nationality and Taxation

Dual nationality may also create taxation issues.

A person may be considered subject to tax obligations by both States.

Domestic tax laws and bilateral tax treaties may provide mechanisms to reduce or avoid double taxation.

Nationality is not, however, the only basis upon which taxation is imposed; residence and source of income may also be relevant.

Dual Nationality and Consular Protection

A dual national may seek consular assistance from either State of nationality.

However, problems may arise when the person is physically present in the other State of nationality.

A State may face greater difficulty providing diplomatic or consular protection to a person who is also a national of the receiving State.

Dual Nationality and State Protection

The existence of dual nationality means that an individual may have legal connections with two States.

This can provide advantages, but it can also create conflicting obligations.

Possible areas include:

• taxation;
• military service;
• criminal jurisdiction;
• political participation;
• diplomatic protection;
• extradition.

Dual Nationality and Human Rights

International human rights law increasingly recognises that nationality should not be arbitrarily removed.

A dual national may retain one nationality even if another nationality is lost.

Therefore, dual nationality can sometimes reduce the risk of statelessness.

For example:

State A nationality withdrawn

State B nationality retained

↓

Person remains a national of State B

Multiple Nationality

Dual nationality is one form of multiple nationality.

Dual nationality

Two nationalities.

Multiple nationality

Two or more nationalities.

Thus:

Dual nationality ⊂ Multiple nationality

Dual Nationality vs Statelessness

These concepts are opposites in an important sense.

Dual nationality → two nationalities

Statelessness → no nationality

A person with dual nationality has multiple legal bonds with States, while a stateless person lacks nationality of any State.

Advantages of Dual Nationality

Dual nationality may provide:

• greater freedom of residence;
• ability to work in both States;
• political rights where permitted;
• access to public services;
• family and property connections;
• greater mobility.

The precise rights depend upon domestic law.

Problems of Dual Nationality

Dual nationality may create:

• conflicting legal obligations;
• taxation issues;
• military service obligations;
• competing jurisdiction;
• extradition problems;
• diplomatic protection disputes;
• questions concerning political allegiance.

Loss of One Nationality

A dual national may lose one nationality through:

• voluntary renunciation;
• deprivation;
• statutory provisions;
• State succession;
• other grounds under domestic law.

If the person retains the second nationality, they do not become stateless.

International Law and Sovereignty

Nationality remains primarily a matter of domestic law.

States determine:

• who may acquire nationality;
• whether dual nationality is permitted;
• whether nationality may be renounced;
• whether multiple nationality is recognised.

However, international rules regulate the consequences of these decisions.

Important Cases

Nottebohm (1955)

Important for genuine/effective nationality and diplomatic protection.

Mergé Claim (1955)

Important for dual nationality and diplomatic protection against a State of which the person is also a national.

Barcelona Traction (1970)

Important for nationality in relation to corporations and diplomatic protection, although it does not concern dual nationality in the same way as Mergé.

Common Confusions

Is dual nationality illegal?

No. International Law does not generally prohibit it.

Does every State recognise dual nationality?

No. Domestic laws differ significantly.

Can dual nationality arise automatically?

Yes, particularly where jus soli and jus sanguinis overlap.

Can naturalisation create dual nationality?

Yes, if the person’s original State permits retention of nationality.

Can a person have more than two nationalities?

Yes, where the laws of the relevant States permit it.

Can a dual national receive diplomatic protection?

Potentially, but special rules apply, particularly when the claim is against the other State of nationality.

What is the Mergé principle?

It is traditionally associated with the restriction on diplomatic protection by one State against another State of which the injured person is also a national.

What is predominant nationality?

The nationality that is predominant in the circumstances relevant to diplomatic protection under the modern ILC framework.

What is the leading case concerning genuine nationality?

Nottebohm (1955).

Topic at a Glance

Point Position Meaning Nationality of two States Main source Domestic nationality laws International Law Does not generally prohibit dual nationality Common cause Jus soli + jus sanguinis Naturalisation May create dual nationality Multiple nationality Two or more nationalities Key issue Conflicting legal obligations Diplomatic protection Special rules apply Respondent State Predominant nationality may become relevant Mergé Claim Important dual nationality authority Nottebohm Genuine/effective nationality Jurisdiction Two States may potentially claim nationality jurisdiction Extradition Nationality may affect extradition Military service Conflicting obligations possible Taxation Double taxation issues may arise Statelessness Dual nationality can prevent statelessness

Quick Revision

• Dual nationality means possessing the nationality of two States simultaneously.
• It can arise through:
  • jus soli;
  • jus sanguinis;
  • naturalisation;
  • marriage-related nationality laws;
  • adoption;
  • State succession.
• International Law does not generally prohibit dual nationality.
• Domestic law determines whether dual nationality is recognised.
• Dual nationality can create conflicts concerning:
  • jurisdiction;
  • extradition;
  • taxation;
  • military service;
  • diplomatic protection.
• Mergé Claim (1955) → important for diplomatic protection involving dual nationals.
• Nottebohm (1955) → genuine/effective nationality.
• Under the modern ILC framework, predominant nationality may be relevant where diplomatic protection is sought against another State of nationality.
• Dual nationality ≠ statelessness.
• Dual nationality can sometimes reduce the risk of statelessness.
• The essential principle is:

Dual nationality is the simultaneous possession of two nationalities, generally arising from the operation of different domestic nationality laws, and it may create complex questions concerning jurisdiction, diplomatic protection and conflicting State obligations.

Conclusion

Dual nationality occurs when an individual is legally recognised as a national of two States simultaneously. It commonly results from differences between nationality laws, particularly where jus soli and jus sanguinis operate together, or where a State permits a person to retain their original nationality after naturalisation. International Law does not generally prohibit dual nationality, leaving its recognition primarily to domestic law. However, dual nationality creates important international legal questions. A person may potentially be subject to the jurisdiction of both States of nationality, may face competing military or taxation obligations, and may encounter special rules concerning extradition and consular protection. The most significant issue arises in diplomatic protection, particularly where a dual national seeks protection against one of the States of which they are a national. The Mergé Claim and the ILC Draft Articles on Diplomatic Protection, 2006 are important in this context, while Nottebohm is central to discussions of genuine or effective nationality. Dual nationality should also be distinguished from statelessness, as a dual national possesses two legal bonds with States whereas a stateless person possesses none. Ultimately, dual nationality demonstrates the complex interaction between domestic nationality laws and the international legal consequences of nationality.