Irish nationality law is contained in the provisions of the Irish Nationality and Citizenship Acts 1956 to 2004 and in the relevant provisions of the Irish Constitution. A person may be an Irish citizen through birth, descent, marriage to an Irish citizen or through naturalisation. The law grants citizenship to individuals born in Northern Ireland under the same conditions as those born in the Republic of Ireland.

Acquisition of citizenship

At birth

A person born on the island of Ireland on or after 1 January 2005:.

Nationality law is the law in each country and in each jurisdiction within each country which defines the rights and obligations of citizenship within the jurisdiction and the manner in which citizenship is acquired as well as how citizenship may be lost. A person who is not a citizen of the country is generally regarded as a foreigner, also referred to as an alien. A person who has no recognised nationality or citizenship is regarded as stateless. By international custom, each sovereign state has the right to determine who it will recognise as its nationals and citizens. Such determinations may be made by custom, statutory law, or case law (precedent), or some combination. In some cases, the determination may be governed by public international law—for example, by treaties and the European Convention on Nationality.

Principles

Broadly speaking, nationality law is based either on jus soli or jus sanguinis, or on a combination of the two and even due to marital relations. Jus soli (Latin: the law of the soil) is the principle by which a child born within a country's territorial jurisdiction acquires that country's nationality. Jus sanguinis (Latin: the law of the blood) is the principle by which a child acquires the nationality of his or her parents. Today, most if not all countries apply a mixture of these two principles: neither granting citizenship to everyone born within the country's jurisdiction, nor denying citizenship to the children born abroad.

Nationality is the legal relationship between a person and a state. Nationality affords the state jurisdiction over the person and affords the person the protection of the state. What these rights and duties are vary from state to state.

By custom and international conventions, it is the right of each state to determine who its nationals are. Such determinations are part of nationality law. In some cases, determinations of nationality are also governed by public international law—for example, by treaties on statelessness and the European Convention on Nationality.

Nationality differs technically and legally from citizenship, which is a different legal relationship between a person and a country. The noun national can include both citizens and non-citizens. The most common distinguishing feature of citizenship is that citizens have the right to participate in the political life of the state, such as by voting or standing for election. However, in most modern countries all nationals are citizens of the state, and full citizens are always nationals of the state.