jus soli, in legal theory, the rule or law that provides that citizenship is acquired by birth within the territory of the state, regardless of parental citizenship. Originating in English common law, jus soli serves as the basis for citizenship in nearly every nation-state in the Western Hemisphere and as the foundation for the Fourteenth Amendment to the Constitution of the United States. It differs from jus sanguinis (“right of blood”), which grants citizenship on the basis of the citizenship possessed by one’s parent or parents. By the early 21st century, 35 countries were granting unrestricted birthright citizenship, and an additional 40 countries were providing birthright citizenship with restrictions, such as requiring one or more parents to be citizens or residents of that country or requiring the completion of a minimum residency period before birthright citizenship is granted.
Citizenship is a relationship between an individual and the state in which the individual is bound by obligations to the state, and the state grants a suite of rights to the individual in return. Jus soli presupposes a civic-republican conception of the core nation according to which national membership depends on acquiring, through the process of becoming socialized to the rules and norms of the state, loyalty to state institutions and acceptance of a shared political culture.
The rule is often seen as a hedge against statelessness (the condition of either not possessing or being denied a nationality, which prevents an individual from obtaining services such as an education, employment, health care, or freedom of movement within a country). Statelessness often prevents individuals from accessing basic human rights in the countries in which they reside, and this condition can be passed on to future generations. The rule of jus soli effectively prevents the inheritance of statelessness by offspring. Nevertheless, a condition of statelessness may still arise, as when a citizen of one country, who, when migrating to another, cannot prove their citizenship because of missing documentation or existing documentation being discounted or ignored by officials in the new country, and thus both the migrant parent and any of their offspring born in the originating country cannot prove their nationality.