The Third Dáil, was both the Provisional Parliament or the Constituent Assembly of Southern Ireland from 9 August to 6 December 1922; and the lower house (Dáil Éireann) of the Oireachtas of the Irish Free State from 6 December 1922 until 9 August 1923.
The elections to the Third Dáil took place on 16 June 1922. They occurred under the system of proportional representation by means of the single transferable vote. Unlike the Second Dáil, which was notionally elected by the whole island of Ireland, the Third Dáil would not include members elected from Northern Ireland. Since the election of the Second Dáil in 1921, Sinn Féin, the only political party represented in the Dáil, had split into pro and anti-treaty factions and these two factions became the major contestants of the 1922 elections. Despite a pact between the two factions, the elections were therefore effectively a de facto referendum on the Anglo-Irish Treaty. The pro-treaty side won a majority of seats and the anti-treaty faction boycotted the assembly, refusing to recognise the body as the legitimate heir to the Second Dáil, and the Civil War broke out shortly afterwards.
Article 17 of the Anglo-Irish Treaty provided that:
Article 17 therefore envisaged by way of "provisional arrangement" the creation of a provisional government. For the purposes of giving effect to Article 17, the Irish Free State (Agreement) Act 1922, an act of the Parliament of the United Kingdom provided in Section 1(2) that:
The Third Dáil was:
Both theories agree that it was a "constituent assembly".
Rival political theories existed in Ireland at the time. Ireland since 1919 had been governed under two rival political theories. To nationalists and republicans, an assembly of Irish members of parliament (who adopted the equivalent Irish language term Teachta Dála or TD) had formed in Dublin in 1919 and was seen as the valid parliament of the Irish People from which the Irish Republic received its sovereignty. Each Dáil in turn was the successor of the earlier one and the legitimate parliament of the Irish Republic. The Second Dáil was chosen through an election in 1921 called by the British administration in Ireland, the elected republican members forming themselves into the Second Dáil rather than the Parliament of Southern Ireland they were elected to.