Nationality law

Nationality law is the law of a sovereign state, and of each of its jurisdictions, that defines the legal manner in which a national identity is acquired and how it may be lost. In international law, the legal means to acquire nationality and formal membership in a nation are separated from the relationship between a national and the nation, known as citizenship. Some nations domestically use the terms interchangeably, though by the 20th century, nationality had commonly come to mean the status of belonging to a particular nation with no regard to the type of governance which established a relationship between the nation and its people. In law, nationality describes the relationship of a national to the state under international law and citizenship describes the relationship of a citizen within the state under domestic statutes. Different regulatory agencies monitor legal compliance for nationality and citizenship. A person in a country of which he or she is not a national is generally regarded by that country as a foreigner or alien. When the sovereignty over a territory is transferred from one state to another, individuals may be given the right of option of nationality. A person who has no recognised nationality to any jurisdiction is regarded as stateless.

Nationality law can be broadly categorized into three principles:

Laws may be based on any one of these principles, but they commonly reflect a combination of all three principles. Generally speaking, countries in the Americas have a strong jus soli heritage.

Jus soli is the principle, whereby birth on a country's territorial jurisdiction—e.g., 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. This law was inherited by the colonies and subsequently codified into their own domestic laws, such as in the United States, Canada, Australia, etc.

Jus soli laws are not 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 nationality if the child's father (regardless of parental nationality) was born in the same territory. Sometimes jus soli will be restricted by age.

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

Jus sanguinis is the principle whereby the nationality of a person is dictated by their blood (i.e., parentage or ancestry). For instance, in Italy, nationality may be transmitted perpetually if one can find an Italian ancestor up until the founding of the Italian state in their lineage. By contrast, other states may restrict their jus sanguinis transmission of nationality up to the registration of the second generation down the family line.

Some states automatically confer nationality on the basis of marriage. A prominent example of a country with jus matrimonii laws is Cape Verde.