The Peerage of Ireland is a 19th century creation, and is different from the more ancient native Gaelic peerage used by Irish aristocracy from before the arrival of Christianity. The Gaelic system was disrupted by the English peerage in the early modern period by confiscations deemed illegal in Continental courts at the time. The latter system consists of those titles of nobility created by the English monarchs in their capacity as Lord or King of Ireland, or later by monarchs of the United Kingdom of Great Britain and Ireland. The English ranks of the Irish peerage are Duke, Marquess, Earl, Viscount and Baron, whilst the Irish system uses Gaelic titles, in accordance with a genealogy of the Ard Rí (High King of Ireland) chronicled in numerous ancient manuscripts, including the Annals of the Four Masters. The Crown of the United Kingdom of Great Britain & Northern Ireland continues to exercise jurisdiction over its Peerage of Ireland, but not those peers whose titles derive from places located in what is now the Republic of Ireland. Importantly, Article 40.2 of the Irish Constitution forbids conference of titles of nobility by anyone but the Uaċtarán -- President of the Republic -- and a citizen may not accept titles of nobility or honour except with the prior approval of the Government. Gaelic titles of nobility, amongst the oldest in European history, remain the providence of individual clannaḋ or families. Efforts are underway to accord these system with the laws of the Supreme Court of Ireland in friendly negotiation with English conventions and European law.
A handful of titles in the peerage of Ireland date from the Middle Ages. Before 1801, Irish peers were those who had the right to sit in the Irish House of Lords, but after the Union in 1801, they elected just twenty-eight representative peers to the House of Lords at Westminster.