What is the Alternative Vote (AV)?

Campaign group the Electoral Reform Society says "The Alternative Vote (AV) is the electoral system being proposed as a replacement for the existing First Past the Post (FPTP) method of electing MPs.

It is similar to FPTP in that the country is divided into constituencies, each of which has one MP.

It is also similar to FPTP in that voters choose between candidates, not party lists - unlike the systems used for the Scottish Parliament, Welsh Assembly and European Parliament.

It is different from FPTP because instead of marking an 'X' by the candidate you want to win, you put a number '1' by your favourite candidate, '2' by your second-favourite candidate, and so on.

Counting an AV election is different from counting a FPTP election. The first stage is to count up the first preferences (number 1 votes) for each candidate. If a candidate has a majority of votes (i.e. over 50 per cent) they are elected straight away.

If no candidate has a majority of the vote, the lowest-placed candidate is out of the running and the votes for that candidate are looked at again to see which candidate each of their supporters wanted as their second choice. These second choice votes are added to the votes for the remaining candidates. If someone has a majority now, they are elected. If not, the bottom remaining candidate is out of the running, and the process repeats until someone does have a majority of the vote.

Real-world application of AV:

• Australian House of Representatives

• Australian Legislative Assemblies ("lower houses") of all states and territories (bar Tasmania and the Australian Capital Territory, which both use STV)

• Australian Legislative Council in Tasmania

• Irish Presidential election

• By-elections to the Dáil (the lower house of the Irish Parliament)

• By-elections to the Northern Ireland Assembly

• Papua New Guinea National Parliament (1964-1975 and from 2007).

• Fijian House of Representatives

• Numerous American Mayoral and district elections, as well as Student Union elections

Arguments used in support of AV

• All MPs would have the support of a majority of their constituents.

• It retains the same constituencies, meaning no need to redraw boundaries, and no overt erosion of the constituency-MP link

• It more accurately reflects public opinion of extremist parties, who are unlikely to gain many second-preference votes

• Coalition governments are no more likely to arise under AV than under First-Past-the-Post

• It eliminates the need for tactical voting. Electors can vote for their first-choice candidate without fear of wasting their vote

• A change to AV could be a step towards the adoption of STV

• It encourages candidates to chase second- and third-preferences, which lessens the need for negative campaigning (one don't want to slag off a candidate whose second preferences one wants) and rewards broad-church policies

Arguments used against AV

• It can be less proportional than First-Past-the-Post

• It does very little to improve the voice of traditionally under-represented groups in parliament, strengthening the dominance of the 'central' viewpoint

• There is no transfer of power from party authority to the voters

• In a broadly three-way race, where there are two strong parties who actively dislike each other and a third 'compromise' candidate sitting in between, the compromise candidate is likely to be defeated in the first round, despite the fact that they could well be the most universally acceptable option.

Related items and external links

Nick Clegg's statement on political and constitutional reform.

FairerVotes.

Electoral Reform Society AV FAQ.

ERS Voting Systems Guide.

BBC Q&A: Electoral reform and proportional representation.

LibDemVoice Opinion: Why Lib Dems should have no reservations about campaigning for AV.

Labour use AV in leadership elections.

Compare 2010 general election under AV or PR.