One member, one vote
One member, one vote (OMOV), as used in the parliamentary politics of the United Kingdom, Canada, and the Canadian provinces, is a proposal to select party leaders and/or determine party policy, by a direct vote of the members of each party. Traditionally, these objectives have been accomplished either by a party convention, a vote of Members of Parliament, or some form of electoral college. OMOV backers claim that OMOV enhances the practice of democracy, because ordinary citizens will be able to participate. Detractors counter that allowing those unversed in the issues to help make decisions makes for bad governance.
In English-speaking Canada, the principle of OMOV has for years been a major commitment of Vaughan L. Baird. Long a proponent of the election process that empowers all members of a party to choose their leaders, Baird was instrumental in having the provincial constituency of Morris, Manitoba successfully put forward the principle of OMOV to the provincial Progressive Conservative Party on 5 November 1985. Immediately after the Morris victory, Baird wrote to every national and provincial party in Canada and urged them to do the same. Soon after, the Manitoba Liberal Party adopted the principle. Alberta PCs used the method in electing Ralph Klein as their new leader in December 1992.
Manitoba PCs adopted the process in early 1987, but the hierarchy of the PC Party had it revoked. Though again adopted by the party in 1994, OMOV was revoked a second time in November 1995. Finally, on November 17, 2001, by almost unanimous consent (only three votes against the motion), OMOV was passed by the Progressive Conservative Party of Manitoba. Thus after 16 years of effort, the vote for leadership of the provincial PC party was democratized.
Also in 1995, the New Democratic Party moved some way towards OMOV when they developed a series of regional primary elections prior to their convention. In the subsequent contest, he party went further adopted a modified OMOV process for the 2003 NDP leadership election in which the vote was calculated so that ballots cast by labour delegates had 25% weight in the total result, while votes cast by all party members on an OMOV had a weight of 75%. When the federal Liberal government changed the election finances law, soon after Jack Layton won the NDP's leadership in the modified OMOV election on January 23, 2003, the party implemented full OMOV for its next leadership convention.
More recently in Canada, the Alberta Progressive Conservatives elected a new leader, Ed Stelmach, who succeeded former premier Ralph Klein, utilizing the OMOV system. 97,000 people voted in December 2006.
The Conservative Party of Canada uses a weighted OMOV system in which all ridings are accorded an equal number of points and those points are distributed to candidates proportionately to how party members in that riding vote. The Canadian Alliance used a pure OMOV system but in merger negotiations with the Progressive Conservative Party of Canada it was agreed to adopt the weighted system used in the 1998 Progressive Conservative leadership election in order to encourage leadership candidates to seek support across the country.
In 2009, the Liberal Party of Canada adopted a weighted membership vote in which each riding counts equally in the final tally. This is not a one member, one vote system because, by definition, members have a variable number of votes depending on the riding they live in. However, it is similar to one member, one vote in the sense that every party member is entitled to cast a ballot. Future leadership elections will be conducted according to the same weighted process used by the Conservative Party. The 2009 convention was conducted according to the old rules. However, as this convention did not feature a contested race but was a ratification of Michael Ignatieff's leadership, the last example of a full-blown delegated federal leadership convention being the 2006 convention that elected Stéphane Dion.
United Kingdom 
In the United Kingdom, the methods of selecting party leaders gradually and in some cases slowly developed as parliamentary parties took shape and grew more rigid over time. In some cases, leadership selection methods for British political parties were not developed until many decades after their counterparts elsewhere in the Commonwealth had long-established methods for electing leaders - for example, the Conservative Party did not adopt a formal method for choosing its leaders until 1965. Traditionally, Members of Parliament have usually played a major role in selecting a party leaders, based largely on the belief that since a leader had to work closely with his parliamentary party, their views on who the leader should be had to be paramount. In recent years, all major parties have implemented reforms to allow ordinary party members a say in the choosing of a new leader, while still allowing MPs a central role in the leadership selection process.
During his brief time as leader of the Labour Party between 1992–94, John Smith abolished the trade union block vote at Labour Party conferences, and replaced it with a system of one member one vote. All Labour Party members are also entitled to vote for the Leader and Deputy Leader of the party as part of an electoral college which includes Members of Parliament (MPs), Members of the European Parliament and trade unions.
In January 1998, the OMOV principle was adopted as part of the series of reforms of the Conservative Party. The MPs would choose two candidates to go to a vote by all Conservative members.
The system was first used by the Conservatives in the 2001 leadership election to replace William Hague. A run off by various candidates led to Iain Duncan Smith and Kenneth Clarke being put forward to a vote of all Conservative members, with the final result announced on September 12, 2001. The eligible voters were 328,000 members of the Conservative Party of which 79% of the voters exercised their rights on said date. Duncan Smith became the new Leader of the Conservative Party with 61% of the votes (155,933 votes). Kenneth Clarke obtained 39% of the votes (100,544 votes).
In the 2003 leadership election no ballot took place, since Michael Howard was unopposed in standing to replace Duncan Smith - but the two candidate run off was employed again two years later. On December 6, 2005, it was announced that David Cameron had been chosen by the Conservative members to be the new leader over David Davis. Cameron had 134,446 votes compared to Davis’ 64,398 votes, making a total number of 198,844 votes.
Thus both the Labour Party and the Conservative Party in Britain now elect their leaders by processes which include all their members having the right to vote at some point.
On the other hand, the Liberal Democrats have always elected their leaders through a one member, one vote system since the party's foundation in 1988. Rather than having a runoff the Liberal Democrats use the Alternative Vote system of preference voting. Liberal Democrat MPs have no special voting rights when choosing the leader - however, a prospective candidate must be a sitting Liberal Democrat MP with the support of at least ten percent of the Parliamentary Party in order to stand in a leadership election.