Nationality law

Nationality law (or citizenship law) is the law in each country and in each jurisdiction within each country which defines the rights and obligations of citizenship within the jurisdiction and the manner in which citizenship is acquired as well as how citizenship may be lost. A person who is not a citizen of the country is generally regarded as a foreigner, also referred to as an alien. A person who has no recognised nationality or citizenship is regarded as stateless.


Nationality law can be broadly categorised into three principles, jus soli, or right by birth on the soil, jus sanguinis or right of the blood, jus matriomii, or right of marriage. Laws may be based on any of these principles, but commonly is a combination of all three principles. Generally speaking, new world countries have a strong jus soli heritage (along with common law countries, until very recently, with the exception of the United States and Canada).

Jus soli

Jus soli is the principle, whereby birth on a country's territorial jurisdiction; eg, land, or in some cases, vessel registered as being registered as under the jurisdiction of that country (aeroplanes, ships), confers nationality of the country of birth to the child, in most countries this originated from the English common law tradition that all persons born on the King's land owed an allegiance to the King, and this law was inherited by the colonies and subsequently codified into their own domestic laws, see United States, Canada, Australia, etc.

Jus soli laws aren't always absolute. Sometimes countries with jus soli laws require lawful residence in the country before the authorities will observe this right, such as in Cambodia or Thailand. Sometimes jus soli laws only operate generationally, such as in some Middle Eastern countries, where a child born in the territory will only acquire citizenship if the child's father (regardless of nationality) was born in the same territory. Sometimes jus soli will be restricted by age.

There is also an intersection between the principles, where only persons of a certain race or blood, will acquire nationality at birth. For instance in Liberia, African born persons will acquire nationality, whereas those of non-African origin will not be entitled to this privilege.

Jus sanguinis

Jus sanguinis is the principle whereby someone's blood dictates nationality of that person. For instance, in Italy; citizenship may be transmitted perpetually if one can find an Italian ancestor up until the founding of the Italian state in their lineage. Whereas other states may restrict their jus sanguinis transmission of nationality up to the registration of the second generation down the family line.

Jus matriomii and marriage

Some states automatically confer nationality on the basis of marriage. Cape Verde is a prominent example where upon marriage, and request for the citizenship, nationality is automatically conferred. Countries have in the past regarded marriage as an important status changing event in people's' lives and encouraged the special relationship that exists between spouses, sentiments which continue to be valued today. The common practice within and among states at the beginning of the 20th century was that a woman should have the nationality of her husband; i.e., upon marrying a foreigner the wife would automatically acquire the nationality of her husband, and lose her previous nationality, often with the reciprocal recognition by the other country. Even after the nationality of a married woman was no longer dependent on the nationality of her husband, legal provisions were still retained which automatically naturalised married women, and sometimes married men as well. This led to a number of problems, such as loss of the spouses' original nationality, the spouse losing the right to consular assistance (since consular assistance cannot be provided to nationals under the jurisdiction of a foreign state of which they are also nationals), and men becoming subject to military service obligations. There has been a shift towards a principle that neither marriage nor dissolution of marriage automatically affecting the nationality of either spouse, nor of a change of nationality by one spouse during marriage automatically affecting the nationality of their spouse. However, in many jurisdictions spouses can still obtain special and fast processing of applications for naturalisation.

Limits to nationality law

By international custom, each sovereign state generally has the right to freely determine who it will recognise as its nationals and citizens.[1] Such determinations may be made by custom, statutory law, or case law (precedent), or some combination. In some cases, the determination may be governed by public international law—for example, by treaties and the European Convention on Nationality.

Nevertheless, state's rights to determine who their nationals are is not absolute and, in particular, States must comply with their human rights obligations concerning the granting and loss of nationality. In particular, citizens must not be arbitrarily deprived of their nationality.[2] The right to a nationality and the prohibition against depriving ones nationality is codified in article 15 of The Universal Declaration of Human Rights.

Article 1 of the Convention on Certain Questions Relating to the Conflict of Nationality Laws states:

It is for each State to determine under its own law who are its nationals. This law shall be recognised by other States in so far as it is consistent with international conventions, international custom, and the principles of law generally recognised with regard to nationality.[3]

The Inter-American Court of Human Rights went further in limiting state's right to determine nationality:

the manner in which States regulate matters bearing on nationality cannot today be deemed within their sole jurisdiction; [the powers enjoyed by the States in that area] are also circumscribed by their obligations to ensure the full protection of human rights[4]


Most states today allow for aliens to acquire a nationality via a process known as naturalization on the basis of long-term residence and other conditions. This process and the conditions it entails are detailed in the states' nationality laws. Some nationality laws have special provisions to make it easier for diaspora populations to become citizens.