Instant-runoff voting (IRV) is a ranked voting method used in single-winner elections. IRV is also known outside the US as the alternative vote (AV) or preferential voting. IRV is known by different names in the various countries in which it is used. It is also known as the 'Alternative Vote', 'Ranked Choice Voting', and 'Preferential Voting', although IRV is only one of many ranked (or preferential) voting systems.
Today it is in use at the national level to elect the Australian House of Representatives, the National Parliament of Papua New Guinea, the President of Ireland and President of India. In Australia it is also used for elections to the legislative assemblies (lower houses) of all states and territories except Tasmania and the Australian Capital Territory, and for the Tasmanian Legislative Council (upper house).
IRV is also used in some municipal elections in Australia, the United States, United Kingdom and New Zealand. Because of its relationship to the Single Transferable Vote (STV) system, IRV is used for by-elections and elections with only a single winner (such as elections for the President of Ireland) in some jurisdictions that use STV for ordinary parliamentary elections, such as the Republic of Ireland and Scotland.
Instant-runoff voting is based on the Single Transferable Vote electoral system, developed by Hill in 1819, Hare in 1857, and Andrae in 1855. Unlike IRV, the Single Transferable Vote was designed as a form of proportional representation involving multi-seat constituencies, while IRV is a majoritarian method, where minority sentiment goes un-represented.
It is also known as Ware's method, after William Robert Ware, the founder of the schools of architecture at the Massachusetts Institute of Technology (MIT) and Columbia University, who, while describing the experience of holding a demonstration single transferable vote election in 1871, mentioned that a similar method could be used for single-winner elections.
IRV was adopted for the Australian House of Representatives in 1918 and has been used to elect the President of Ireland since the office came into being in 1937. It was introduced in Fiji in 1999 and in Papua New Guinea in 2007.
IRV in its true form (what was called Alternative Voting at the time) was first used in Australia in 1909.
History of the use of IRV by country
Australia The first known use of an IRV-like method in a governmental election was in the 1893 general election in the Colony of Queensland (in present-day Australia). The variant used for this election was a "contingent vote", where all candidates but two are eliminated in the first round, with one of the last two elected by majority after votes of the others are transferred. Queensland used contingent voting until 1942, one of the longest uses of the system anywhere.Bowler and Grofman, Elections in Australia, Ireland and Malta, p. 40
IRV in its true form (what was called Alternative Voting at the time) was first used in Western Australia, in the 1908 state election. The lower houses of Australian states (except Tasmania and ACT) and the Australian House of Representatives are elected through IRV. The last state to adopt AV was Queensland in 1962, It had switched from contingent voting to single-member plurality in 1942.Farrell and McAllister, The Australian Electoral System, p. 50 Multi-winner STV of the Hare-Clark version was introduced for the Tasmanian House of Assembly at the 1909 state election. The Australian Capital Territory used party-list proportional representation from 1989 until 1995 when it adopted STV.Farrell and McAllister, The Australian Electoral System, p. 72, 87
IRV was introduced for federal (nationwide) elections in Australia after the Swan by-election in October 1918, in response to the rise of the conservative Country Party, representing small farmers. The Country Party split the non-Labor vote in conservative country areas, allowing Labor candidates to win without a majority of the vote. The conservative government of Billy Hughes introduced IRV (in Australia called "preferential voting") as a means of allowing competition between the Coalition parties without putting seats at risk. It was first used at the Corangamite by-election on 14 December 1918, and at a national level at the 1919 election. IRV continued to benefit the Coalition until the 1990 election, when for the first time Labor obtained a net benefit from IRV.
IRV (in Australia called preferential voting) was introduced for House of Representatives elections in Australia after the Swan by-election in October 1918, when the conservative Country Party, representing small farmers, split the non-Labor vote in conservative country areas, allowing Labor candidates to win on a first-past-the-post vote then in place. The conservative Nationalist government of Billy Hughes introduced preferential voting to enable the Coalition parties to field candidates in the same electorates without putting Coalition seats at risk. It was first used at the Corangamite by-election on 14 December 1918, and nationwide at the 1919 election. Preferential voting continued to benefit the Coalition until the 1990 election, when for the first time the Labor Bob Hawke government obtained a net benefit from preferential voting.
Ballot papers are marked with the order of preferences: 1, 2, 3, etc. Counting of the ballot papers proceeds and when no candidate receives more than 50% of the first preference vote (candidates with a number one), the candidate with the fewest first preference votes is eliminated and that candidate's votes are distributed to the remaining candidates. The process continues until a candidate accumulates 50% plus one vote, or a simple majority. Counting will continue to finality, which results in what is referred to as the two-party preferred vote, which expresses the electorate's voting preference equivalent to a 2-person election of the two most popular candidates. Most council (local government) elections also use the method, as do the lower house elections of four states (New South Wales, South Australia, Victoria and Western Australia), the sole house of one state (Queensland) and one territory (the Northern Territory) and the upper house of one other state (Tasmania).
A study of the 2007 federal election found that every House of Representatives electorate had at least four candidates, and the average number of candidates was seven. 76 candidates depended on preferences to win, which represented more than half of the 150 winners.
Preferential voting is used for most state and local elections in Australia, but sometimes with optional preferential voting where voters are allowed to limit their number of rankings. The Australian Senate, the upper houses of four states (New South Wales, South Australia, Victoria and Western Australia), the lower house of one state (Tasmania) and the sole house of the Australian Capital Territory, use the multi-winner single transferable vote system.
In 1955, IRV was used to elect councils in five municipalities in Tasmania - Burnie, Devonport, Kentish, Latrobe and Ulverstone - and in Hobart to elect the mayor.
Combined How-To-Vote-Card Combined HTVC in Boothby, SA
Bosnia In 2000, Bosnia used IRV for its election.
Canada Under the name 'preferential' or 'elimination ballot' or alternative vote, IRV was used in the British Columbia's general elections of 1952 and 1953. IRV was brought in by the governing coalition consisting of the Liberal and Conservative parties to gain advantage over the rising CCF. But the election did not work out as the coalition partners expected.
Provincially, British Columbia used a mixture of voting methods to elect their members of the Legislative Assembly (MLAs): single-member districts using first-past-the-post and multi-member districts using through block voting. Elections in BC from the province's creation until the 1990 election were held under a mix of multi-member and single-member districts, with district types often being changed back and forth from one election to the next. Through almost all of BC's history, seats were filled by plurality elections. The only exceptions were the 1952 and 1953 elections where Instant-runoff voting was used.
Through the 1940s, the province was governed by a coalition of the British Columbia Conservative Party (the Conservatives) and the British Columbia Liberal Party (the Liberals). Neither party had sufficient electoral support to form government alone, and the coalition allowed these parties to keep the left-of-centre Co-operative Commonwealth Federation (CCF) out of power.
By the 1950s, the coalition had begun to fall apart, resulting in the Conservatives and Liberals having to run for office separately under their own party banners. However, to try to prevent the CCF from being elected, one of the last acts of the coalition government was to introduce the alternative voting system (known today in the US as instant-runoff voting), which was implemented for the 1952 general election. IRV was brought in even in multi-seat districts by the innovation that each seat would be filled by a separate contests, two or even three separate ballots and contests in a district.
In each contest in a district, rather than voting for one candidate by marking an "X" on the ballot, an elector ranked the candidates running in the contest by placing numbers next to their names on the ballot. (They could rank as few or as many candidates as they desired.) The candidate marked with a 1 received the vote in the first count. In the first count, if a candidate received a majority of first preferences marked by voters, that candidate was declared elected with no vote transfers being conducted. If not, the candidate with the fewest votes was dropped and the candidate's ballots were re-allocated to the remaining candidates based on the second choices marked on the ballots. This procedure was repeated again and again if necessary until a candidate received a majority of votes.
The result of using this voting method (plus completely different voting behavior by many BC voters) was the unexpected election of enough MLAs of the British Columbia Social Credit Party (the SoCreds), to form a minority government, with the CCF forming the official opposition. The BC Liberals were reduced to six members in the Legislature. The Conservatives (who changed their party name to the "Progressive Conservatives" in tandem with their federal counterparts) were reduced to four.
The SoCred minority government lasted only nine months before losing a vote in the Legislature and an election having to be called. Alternative voting was again employed in this general election. The result this time was a SoCred majority.