All persons should, by virtue of their essential humanity, enjoy all human rights. Exceptional distinctions, for example between citizens and non-citizens, can be made only if they serve a legitimate State objective and are proportional to the achievement of that objective.

Citizens are persons who have been recognized by a State as having an effective link with it. International law generally leaves to each State the authority to determine who qualifies as a citizen. Citizenship can ordinarily be acquired by being born in the country (known as jus soli or the law of the place), being born to a parent who is a citizen of the country (known as jus sanguinis or the law of blood), naturalization or a combination of these approaches.

A non-citizen is a person who has not been recognized as having these effective links to the country where he or she is located. There are different groups of non-citizens, including permanent residents, migrants, refugees, asylum-seekers, victims of trafficking, foreign students, temporary visitors, other kinds of non-immigrants and stateless people. While each of these groups may have rights based on separate legal regimes, the problems faced by most, if not all, non-citizens are very similar. These common concerns affect approximately 175 million individuals worldwide—or 3 per cent of the world’s population.