Constituency revision is effected by an act of the Oireachtas (parliament) which enumerates the areas included within each constituency.[1] Historically the act was drafted by the government of the day to favour its own party or parties, leading to allegations of gerrymandering by the opposition.[1] The Electoral (Amendment) Act 1959 was struck out in 1961 by the High Court as being repugnant to the Constitution of Ireland because of excessive malapportionment. The hastily enacted replacement, the Electoral (Amendment) Act 1961, relied instead on manipulating district size;[a] the Electoral (Amendment) Act 1974 attempted to do the same, but backfired when a larger-than-anticipated swing resulted in a landslide for the opposition in the 1977 general election.[1] The incoming Taoiseach Jack Lynch promised that future boundary revisions take account of recommendations from an independent commission. Such commissions operated on an ad-hoc basis, beginning with the 1977 European constituency commission whose report was used for the 1979 election.[3] The first Dáil commission's report informed the Electoral (Amendment) Act 1980.[4]
The ad hoc system was superseded when the Electoral Act 1997 placed the Constituency Commission on a statutory footing with fixed terms of reference.[5] These provisions of the 1997 Act were repealed by the Electoral Reform Act 2022. In 2023, the government established the Electoral Commission as a permanent statutory body under the Electoral Reform Act 2022.[6] This assumed functions previously carried out by the Constituency Commission and Local Electoral Area Boundary Committees, as well as handling other functions relating to elections and referendums in the state.[7]
In relation to Dáil constituencies, the commission was required, in observing the relevant provisions of the Constitution of Ireland, to have regard to:[8]
the total number of members of the Dáil, subject to Article 16.2.2° of the Constitution, shall be not less than 166 and not more than 172;[9]
each constituency shall return three, four or five members;
the breaching of county boundaries shall be avoided as far as practicable;
each constituency shall be composed of contiguous areas;
there shall be regard to geographic considerations including significant physical features and the extent of and the density of population in each constituency;
the Commission shall endeavour to maintain continuity in relation to the arrangement of constituencies.
The Commission invited written submissions in relation to both Dáil and European Parliament constituencies from the general public and from each member of the Dáil and Seanad, and the members of the European Parliament from Ireland, registered political parties and Returning officers/County registrars.[10]
The commission presented its report to the Chairman of the Dáil (Ceann Comhairle). The final determination of the constituencies for Dáil Éireann and the European Parliament is a matter for the Oireachtas to prescribe in legislation, as the commission's role was advisory.
^Where the Fianna Fáil party of the then government had less than 50% support, four-seat constituencies were used, so that Fianna Fáil would win two of four seats; where it had more than 50% support, three- or five-seat constituencies would give it two of three, or three of five.[1][2]
^Electoral (Amendment) Act 2009, s. 9: Substitution of Part II of Electoral Act 1997 (No. 4 of 2009, s. 9). Enacted on 24 February 2009. Act of the Oireachtas. Retrieved from Irish Statute Book on 11 November 2021.
^Electoral (Amendment) (Dáil Constituencies) Act 2017, s. 5: Amendment of section 6(2) of Electoral Act 1997 (No. 39 of 2017, s. 5). Enacted on 23 December 2017. Act of the Oireachtas. Retrieved from Irish Statute Book on 11 November 2021.