A person who, under the law of a particular state, is not a citizen of that state. Aliens are usually classified as resident aliens (domiciled in the host country) or transient aliens (temporarily in the host country on business, study, etc.). They are normally subject to certain civil disabilities, such as being ineligible to vote. For the purposes of UK statute law an alien is defined by the British Nationality Act 1981 (in force from 1 January 1983) as a person who is neither a Commonwealth citizen, nor a British protected person, nor a citizen of the Republic of Ireland. At common law, a distinction is drawn between friendly and enemy aliens. The latter comprise not only citizens of hostile states but also all others voluntarily living in enemy territory or carrying on business there; they are subject to additional disabilities. See also allegiance; due diligence; jus sanguinis.