By-elections, also spelled bye-elections (Ireland only) (known as special elections in the United States and the Philippines, and bypolls in India), are used to fill elected offices that have become vacant between general elections.
In most cases these elections occur after the incumbent dies or resigns, but they also occur when the incumbent becomes ineligible to continue in office (because of a recall, ennoblement, criminal conviction, or failure to maintain a minimum attendance). Less commonly, these elections have been called when a constituency election is invalidated by voting irregularities.
The procedure for filling a vacant seat in the House of Commons of England was developed during the Reformation Parliament of the 16th century by Thomas Cromwell; previously a seat had remained empty upon the death of a member. Cromwell devised a new election that would be called by the king at a time of the king's choosing. This made it a simple matter to ensure the seat rewarded an ally of the crown.
By-elections are held in most nations that elect their parliaments through single-member constituencies, whether with or without a runoff round. This includes most Commonwealth countries, such as the United Kingdom, Canada and Pakistan, as well as non-Commonwealth countries such as France. In the UK a writ for a by-election must be issued within three months of a vacancy arising.
In the United States, these contests have been called "special elections" because they do not always occur on Election Day like regular congressional elections. Special elections are held when a seat in the House of Representatives, state legislature, or local legislature becomes vacant. At the federal level, the U.S. Constitution requires that vacancies in the House of Representatives be filled with a special election (unlike the Senate, where it is up to law of the state involved to determine how the vacancy is filled). In most cases where a vacancy is filled through a special election, a primary will also be held to determine which candidates will represent the major parties.
When one seat in a proportional representation constituency becomes vacant, the consequences vary. For example, a by-election may be held to fill just the vacancy or all the seats in the constituency could be contested in the by-election.
Scotland and New Zealand still hold by-elections, despite having adopted the mixed-member proportional representation system, in which some members are chosen by party lists. In both countries, by-elections where voters elect their preferred candidate are only used to fill a vacancy in a constituency seat. For example, the death of Donald Dewar resulted in a by-election for the constituency of Glasgow Anniesland. If a vacancy arises from the death or resignation of a party list member, the next unelected candidate on the party list is offered the seat. If that candidate has died or declines the seat, it is offered to subsequent candidates on the list until one accepts the seat. For example, on the resignation of Darren Hughes in March 2011, Louisa Wall was elected after all the five candidates above her on the New Zealand Labour Party's list declined the seat. The Republic of Ireland holds by-elections despite electing members in multi-member constituencies by the single transferable vote.
Alternatives to holding a by-election include:
For the Australian Senate (where each State forms a multi-seat constituency voting by single transferable vote), the State Parliament appoints a replacement; in 1977 a referendum amended the Constitution to require that the person appointed must belong to the same political party (if any) as the Senator originally elected to that seat. Those Australian states with an Upper House elected by PR-STV (NSW, Victoria and South Australia) copy the federal Senate model, except for Western Australia, which holds a recount of ballots, with sitting members retaining their seats.
By-elections can be crucial when the ruling party has only a small majority. In parliamentary systems, party discipline is often so strong that the governing party can only lose a vote of no confidence after losing enough by-elections for it to become a minority government. Examples are the Labour government of James Callaghan 1976-1979 and Conservative government of John Major 1992-1997. In the United States Senate, Scott Brown's election in 2010 ended the filibuster-proof supermajority formerly enjoyed by Democrats.
By-elections can also be important if a minority party needs to gain one or more seats in order to gain official party status or the balance of power in a minority or coalition situation. For example, Andrea Horwath's win in an Ontario provincial by-election in 2004 allowed the Ontario New Democratic Party to regain official party status with important results in terms of parliamentary privileges and funding.
Political scientists often caution against overinterpreting by-election results, which non-experts often take as a bellwether. The evidence suggests that whilst they have some predictive power (particularly with margin of victory relative to the districts' normal performance, rather than the win-loss record); other indicators generally provide stronger evidence, and the often small data set of by-elections per election cycle makes it worth extrapolating results cautiously. Seats which have changed hands in "shock" by-elections also often revert to the former party in the next (or a subsequent) general election.
A 2016 study of special elections to the United States House of Representatives found "that while candidate characteristics affect special election outcomes, presidential approval is predictive of special election outcomes as well. Furthermore, we find that the effect of presidential approval on special election outcomes has increased in magnitude from 1995 to 2014, with the 2002 midterm representing an important juncture in the nationalization of special elections."
By-election upsets can have a psychological impact by creating a sense of momentum for one party or a sense of impending defeat for a government. Deborah Grey's 1989 by-election victory in Beaver River was seen as evidence that the newly formed Reform Party of Canada would be a serious political contender and that it posed a serious political threat for the ruling Progressive Conservatives. It also gave important momentum to the new party. Similarly, the upset 1960 by-election victory of Walter Pitman in Peterborough as a "New Party" candidate was a significant boost for the movement to replace the Co-operative Commonwealth Federation with an unnamed "New Party" which would be integrated with the labour movement. Pitman's candidacy in a riding in which the CCF was traditionally weak was seen as a test of this concept and his upset victory convinced the CCF and the labour movement to launch the New Democratic Party (NDP). Gilles Duceppe's 1990 upset landslide by-election victory in Laurier--Sainte-Marie with 66% of the vote on behalf of the newly formed Bloc Québécois was the first electoral test for what was initially a loose parliamentary formation created two months earlier after several Quebec MPs defected from the Progressive Conservative and Liberal parties to protest the failure of the Meech Lake Accord and provided the first indication that the party could be a serious force in the province of Quebec. On the strength of the by-election victory, the BQ went on to be officially formed as a party in 1991 and to win 54 seats in the 1993 federal election, enough to form the Official Opposition.
By-elections may occur singly, or in small bunches, especially if the authority responsible for calling them has discretion over the timing and can procrastinate. They are sometimes bunched to save money, as holding multiple by-elections is likely to cost more than holding a by-election to fill the vacancies all at once. In Canada, in 1978, 15 by-elections were held on a single date, restoring the House of Commons to 264 members. The media called it a "mini-election", a test of the Liberal government's popularity with a general election due in less than a year. The 15 districts stretched from Newfoundland to British Columbia, and produced some unexpected results, for example, an NDP candidate winning in Newfoundland for the first time. In September 1984 the Leader of the Greater London Council Ken Livingstone and 3 other Labour councillors resigned and stood in simultaneous by-elections in an attempt to stage a mini-referendum on the Thatcher government's proposal to abolish the GLC. The effect of the manoeuvre was blunted when the Conservative Party refused to stand candidates against them, and the following year the GLC was abolished.
In Australia, a by-election was held in the seat of Wentworth after the resignation of Malcolm Turnbull. Turnbull, who had been Prime Minister from 2015 until August of that year, had served as the member for Wentworth since 2004. His resignation from parliament in the wake of his ousting as Prime Minister triggered the by-election. Wentworth was considered an exceptionally safe seat for the Liberal Party, and had only ever been held by the Liberal Party and its predecessor parties since its creation in 1901. Former Ambassador to Israel Dave Sharma was preselected as the Liberal Party's candidate for the by-election. The major challenger in the by-election was independent candidate Kerryn Phelps. A huge 17.7% two-party-preferred swing was required for the Liberal Party to lose the seat. Ultimately, the Liberals suffered a 19.0% swing to Phelps, the largest by-election swing in Australian history, which won her the seat. This loss deprived the Liberal Party of its majority in federal Parliament, forcing them into a minority government.
In Canada, General Andrew McNaughton was appointed to Cabinet as Minister of Defence on November 1, 1944, without having a seat in parliament, after his predecessor resigned during the Conscription Crisis of 1944. A by-election was arranged in Grey North which the opposition Progressive Conservative party contested. The major campaign issue became the government's policy of "limited conscription" during World War II, which McNaughton supported, and which the Conservatives rejected. They called, instead, for "full conscription". McNaughton was defeated in the February 5, 1945 by-election. As a result, with confidence in his government undermined, Prime Minister William Lyon Mackenzie King called the 1945 federal election several weeks later; originally he had intended to postpone the election until the war was clearly won. McNaughton sought a seat in the 1945 contest but was again defeated.
In 1942, the Conservatives' Arthur Meighen (who had already served as Prime Minister during the 1920s) sought to re-enter the House of Commons of Canada through a by-election in York South. His surprise defeat at the hand of Joseph Noseworthy of the Co-operative Commonwealth Federation ended his political career, and may also have been a factor in the Conservative Party's decision to move to the left and rebrand itself the Progressive Conservative Party under Meighen's replacement. Noseworthy's victory was also a significant breakthrough for the CCF giving it credibility as a national party where it has previously been seen as a Western Canadian regional protest party.
In Canada, the most recent example of a cabinet minister appointed from outside parliament having to resign after losing a by-election was in 1975, when Minister of Communications Pierre Juneau was appointed to Pierre Trudeau's Liberal cabinet directly from the private sector, and tried to enter parliament through a by-election in Hochelaga. Juneau unexpectedly lost to the Progressive Conservative candidate and resigned from cabinet 10 days after his by-election defeat.
In Ontario, John Tory, leader of the Progressive Conservative Party of Ontario ran in a 2009 by-election in Haliburton--Kawartha Lakes--Brock, after he convinced one of his caucus members to step down, in hopes of re-entering the Ontario legislature. His by-election defeat resulted in his resignation as party leader.
In Hong Kong, pro-democracy camp lost their majority status for the first time in the Geographical constituency part of the Legislative Council of Hong Kong in March 2018 Hong Kong by-elections. By-elections were held due to six pro-democracy lawmakers were disqualified by the High Court of Hong Kong during Oath-taking controversy. The pro-democracy camp was considered safe in de facto first past the post by-election because both pro-democracy camp and pro-Beijing camp would only nominate one candidate to fill in the by-election. However, pro-democracy camp lost twice in Kowloon West, which was considered as a safe seat for the pro-democracy camp.
In Ireland by-elections, a by-election held in Dublin South-West during 2014 provided a very surprising upset. The Sinn Féin candidate, Cathal King, was the favourite to take the seat. Sinn Féin had done extremely well in the area during that year's local elections. Sinn Féin captured high percentages of the first preference vote across the constituency. However, the Anti-Austerity Alliance candidate, Paul Murphy, was elected on the eighth count. Despite Murphy having received a lower first preference total than Cathal King, he outperformed the Sinn Féin candidate in attracting transfers. Murphy then took his seat in the 31st Dáil. As a direct result of this defeat in the by-election, Sinn Féin hardened their stance against Irish Water and called for the complete abolition of water charges in Ireland.
In 1965 the British Foreign Secretary Patrick Gordon Walker stood in the Leyton by-election for election to the UK Parliament, having been defeated in controversial circumstances in Smethwick at the previous year's general election. His appointment as a senior minister while not a member of either house of Parliament was against convention, and he therefore sought to regularise the position by standing in the first available by-election, which was at Leyton in January 1965. However a strong swing against Labour resulted in Gordon Walker's defeat: as a result, he resigned as Foreign Secretary.
A Massachusetts special Senate election held in January 2010 produced a significant upset when Republican Scott Brown won the United States Senate seat formerly held for 47 years by Democrat stalwart Ted Kennedy.