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. A person who has no recognised nationality to any jurisdiction is regarded as stateless.
Nationality law can be broadly categorized into three principles:
jus soli, or right by birth on the soil;
jus sanguinis, or right of the blood; and
jus matrionii, or right of marriage.
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
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.