Various attempts had been made to give Ireland limited regional self-government, known as Home Rule, in the late 19th and early 20th centuries. The First Home Rule Bill of 1886 was defeated in the British House of Commons following intense Unionist and Orange Order opposition which caused a split in the Liberal Party, while the Second Home Rule Bill of 1893, having been passed by the Commons was vetoed by the House of Lords. The Third Home Rule Bill introduced in 1912 by the Irish Parliamentary Party could no longer be vetoed after the passing of the Parliament Act 1911 which removed the power of the Lords to veto bills. They could merely be delayed for two years.
Because of the continuing threat of civil war in Ireland, King George V called the Buckingham Palace Conference where Nationalist and Unionist leaders were invited to seek agreement. The conference eventually failed. Due to controversy over the rival demands of Irish Nationalists, backed up by the Liberals (for all-Ireland home rule), and Irish Unionists, backed up by the Conservatives, for the exclusion of most or all of the province of Ulster. After an amending bill which allowed for Ulster to be temporarily excluded from the working of the Act, it was passed to the statute books and received Royal Assent immediately after the outbreak of the First World War. The Act's implementation was suspended until after what was expected to be a short European war.
"Southern Ireland" was to be all of Ireland except for "the parliamentary counties of Antrim, Armagh, Down, Fermanagh, Londonderry and Tyrone, and the parliamentary boroughs of Belfast and Londonderry" which were to constitute "Northern Ireland". Northern Ireland as defined by the Act, amounting to six of the nine counties of Ulster, was seen as the maximum area within which Unionists could be expected to have a safe majority. This was in spite of the fact that counties Fermanagh and Tyrone had Catholic Nationalist majorities.
At the apex of the governmental system was to be the Lord Lieutenant of Ireland, who would be the Monarch's representative in both of the Irish home rule regions. The system was based on colonial constitutional theories. Executive authority was to be vested in the crown, and in theory not answerable to either parliament. The Lord Lieutenant would appoint a cabinet that did not need parliamentary support. No provision existed for a prime minister.
Such structures matched the theory in the colonial constitutions in Canada and Australia, where in theory powers belonged to the governor-general and there was no theoretical responsibility to parliament. In reality, governments had long come to be chosen from parliament and to be answerable to it. Prime ministerial offices had come into de facto existence. Such developments were also expected to happen in Northern Ireland and Southern Ireland, but technically were not required under the Act.
A Council of Ireland would co-ordinate matters of common concern to the two parliaments, with each parliament possessing the ability, in identical motions, to vote powers to the Council, which it was hoped would evolve into a single Irish parliament. Both parts of Ireland would continue to send a number of MPs to the Westminster parliament. Elections for both lower houses took place in May 1921.
With only the four Unionist MPs (all representing graduates of the Irish Universities) and 15 appointed senators turning up for the state opening of the Southern Ireland Parliament in the Royal College of Science in Dublin (now Government Buildings) in June 1921, the new legislature was suspended. Southern Ireland was ruled, for the time being, directly as a Crown Colony.
The House of Commons of Southern Ireland came back into existence again for a short time under the Anglo–Irish Treaty of 1921, to fulfil two functions. The first was to formally ratify the Treaty, which it did on 14 January 1922, after the Second Dáil (which had authority, in nationalist eyes, for ratifying the Treaty) had done so on 7 January. Secondly, it was required to put in place a Provisional Government, which it did, under General Michael Collins. Collins was then legally installed in office by the Lord Lieutenant, Viscount Fitzalan of Derwent.
Following elections, in June 1922, that created the Third Dáil, the Provisional Government enacted a new constitution for the Irish Free State which came into being on 6 December 1922.
In the aftermath of the creation of the Irish Free State, the Irish Free State (Consequential Provisions) Act adjusted the Northern Ireland system of government slightly to cover the failure of Southern Ireland to function. The office of Lord Lieutenant was abolished and replaced by the Governor of Northern Ireland.
In 1977, John Hume challenged a regulation under the Special Powers Act which allowed any soldier to disperse an assembly of three or more people. Lord Chief Justice of Northern Ireland, Lord Lowry held that the regulation was Ultra Vires under Section 4 of the Government of Ireland Act which forbade the Parliament of Northern Ireland to make laws in respect of the army.