Vote pairing

Vote swapping, also called co-voting or vote pairing, occurs when a voter in one district agrees to vote tactically for a less-preferred candidate or party who has a greater chance of winning in their district, in exchange for a voter from another district voting tactically for the candidate the first voter prefers, because that candidate has a greater possibility of winning in that district.

Vote pairing occurs informally (i.e. without binding agreements), but sometimes with great sophistication in the United States, United Kingdom, and Canada, where voters often use online venues to organize such strategies. In all three countries, the process has been subjected to legal challenge and been deemed legal.

Using UK elections as an example, tactical voting is often between the Labour Party and the Liberal Democrats. There may be one constituency in which the Labour Party and the Conservative Party candidates are running in a tight race, with the Liberal Democrat far behind. In another constituency, the Liberal Democrat may be in a close race with either a Labour or Conservative candidate. A Liberal Democrat voter in the first constituency would agree to vote for the Labour candidate in exchange for a Labour voter from the second constituency voting for the Liberal Democrat candidate, allowing either Labour or the Liberal Democrats to pick up an extra seat from the Conservatives.

Tactical voting has been used since 2000 as a strategy in U.S. presidential elections. In this practice, major party voters from safe states support third-party candidates in exchange for voters from swing states voting for one of the two front runners. Through the United States Electoral College, all of a state's votes go to the winning presidential candidate for that state, no matter how close the margin (Maine and Nebraska excepted). Third-party candidates for president frequently garner no Electoral College votes, but can siphon off total votes from the front runners in order to call attention to their causes. In vote-pairing agreements, third-party supporters in swing states vote strategically with major-party supporters in non-swing states, in the hope that the third-party candidate will get more of the popular vote, while the major-party candidate gets more of the Electoral College vote.

Legality
In the United States, the legality of vote pairing in public elections has been questioned. Opponents claim that it is illegal to give or accept anything that has pecuniary value in exchange for a vote. (Indeed, efforts to buy or sell votes are illegal, and in the 2000 presidential election, there was even a satirical web site for buying and selling votes, vote-auction.com, which was shut down by an Illinois judge.) Proponents for vote pairing respond that vote pairing does not involve any pecuniary or monetary exchange; rather, simply informal, nonbinding agreements between people to vote strategically. Also, vote pairing is a routine practice in legislative bodies, city councils, etc.

On October 30, 2000, eight days before the November 2000 United States presidential elections, California Secretary of State Bill Jones threatened to prosecute voteswap2000.com, a California-based vote pairing website. In response, voteswap2000.com and votexchange2000.com immediately shut their virtual doors. The site operators, Alan Porter (votexchange2000.com) and William Cody (voteswap2000.com), and two potential users of the sites, Patrick Kerr and Steven Lewis, took the state of California to court.

On August 6, 2007, the 9th U.S. Circuit Court of Appeals ruled that "the websites' vote-swapping mechanisms as well as the communication and vote swaps they enabled were constitutionally protected" and California's spurious threats violated the First Amendment. The 9th Circuit did not decide whether the threats violated the U.S. Constitution's Commerce Clause.

"Both the websites' vote-swapping mechanisms and the communication and vote swaps that they enabled were...constitutionally protected. At their core, they amounted to efforts by politically engaged people to support their preferred candidates and to avoid election results that they feared would contravene the preferences of a majority of voters in closely contested states. Whether or not one agrees with these voters' tactics, such efforts, when conducted honestly and without money changing hands, are at the heart of the liberty safeguarded by the First Amendment."

In Canada, vote swapping with other people in Canada is legal per the Elections Act, as long as there is no money or "material benefit" that passes hands in the vote swap agreement. It's also illegal to trick someone using a false identity to influence someone to vote in a different way.

United States presidential election, 2000
The debate regarding the legality of vote pairing peaked during the 2000 presidential election, when there was a strong effort to shut down the U.S. vote-pairing websites. However, the federal Ninth Circuit Court of Appeals eventually ruled against this action, and by the 2004 presidential election there was no such effort to shut down vote pairing.

The debate intensified in the final days of the 2000 election when six Republican state secretaries of state, led by the California Secretary of State Bill Jones, charged that vote-pairing web sites were illegal and threatened criminal charges against their creators. Multiple web sites had sprung up that were matching supporters of the Democratic presidential candidate, Al Gore, in non-swing states, with supporters in swing states of the strongest third-party candidate, Ralph Nader. Some argued that Ralph Nader was drawing support from left leaning Democrats that would otherwise vote for Al Gore. This would have allowed Nader to get more of the popular vote, or at least his fair share of it, and at the same time allowed Gore to perhaps get more of the Electoral College vote.

There are multiple reasons it would be important for Ralph Nader to still get his share of the national popular vote. One is that if he got five percent or more, then he could get federally distributed public funding in the next election. Also, and perhaps more importantly, he could possibly get included in the presidential debates for the next election in 2004. Third parties have protested their exclusion from the presidential debates.

In 2000, many of the vote pairing web sites were hosted in California, and so when the California Secretary of State, Bill Jones, charged that the web sites were illegal and threatened their creators with criminal prosecution, some (but not all) of the sites reluctantly shut down. The American Civil Liberties Union (ACLU) got involved to protect the web sites, seeking a restraining order against Jones and then a permanent injunction against him, alleging that he had violated the constitutional rights of the web site creators. However, the issue would only be resolved after the 2000 election had already occurred. The media at the time gave little coverage to vote pairing, except for how it was being charged as illegal.

It is possible that Jones's threats of criminal charges against the creators of the vote-pair web sites changed the outcome of the 2000 presidential election. One of the web sites, votetrader.org, tallied the number of people who had registered to pair their votes on all the vote-pairing websites. They tallied that 1,412 Nader supporters in Florida had gotten matched with Gore supporters from Republican states (although more likely vote paired with relatives and friends in other states—instead of over the Internet). George W. Bush was certified as winning Florida by only 537 votes—by Florida's Secretary of State, Katherine Harris. The Florida Supreme Court then changed this margin to just 193 votes at most, in their ruling on December 8, 2004. Approximately 2,900,000 people voted for George W. Bush and Al Gore each in Florida, while the number who voted for Ralph Nader was certified at 97,421. If only another 0.2% of the voters for Ralph Nader in Florida had vote paired (about 200 divided by 97,421)—if about 1,600 Nader supporters had vote paired instead of 1,400—Al Gore would have carried the election.

There were numerous other controversies in Florida's vote count: from the Palm Beach County butterfly ballots; to the question of whether Bush would have still won the state in a full recount; to how Katherine Harris, a Republican, was the co-chair of the Bush campaign in Florida at the same time she was the Florida state secretary of state. Notably, the California state secretary of state, Bill Jones, who charged that the vote-pairing web sites were illegal, was also a Republican supporter of George W. Bush. The federal Ninth Circuit Court of Appeals would eventually rule against him, but this decision did not come down until February 6, 2003, long after the 2000 election was already over. In the next presidential election, in 2004, the legality of the vote-pairing web sites went unquestioned. Indeed, the California state secretary of state for the 2004 election (a successor to Bill Jones) publicly announced, before that election, that vote pairing was legal.

United States presidential election, 2016
In United States presidential elections, vote pairing usually comes in the form of voters from "safe" states, or non-swing states, voting for third-party candidates, and voters from swing states voting for their second-preference candidate. This form of vote pairing encourages third-party support while minimizing the risk that the more favored major-party candidate will lose electoral votes in the nationwide election (i.e. the "spoiler effect"). In the 2016 United States presidential election, this usually manifested in the form of supporters in swing states of Libertarian candidate Gary Johnson and Green Party candidate Jill Stein swapping votes with supporters in blue states of Democratic candidate Hillary Clinton.

With other voting systems
Vote pairing is most often used as a strategy in first-past-the-post voting with winner-takes-all constituencies, as they provide the strongest incentives for dishonesty. However, such a strategy can be effective when using ranked-choice voting as well. Instant-runoff systems are particularly vulnerable to the practice because they frequently fail the favorite betrayal criterion, which means casting a first-rank vote for a third-party can cause a "greater evil" candidate to win.

For example, in the 2009 Burlington mayoral election, voters who supported moderate Republican Kurt Wright eliminated Democrat Andy Montroll in the second round, allowing socialist candidate Bob Kiss to win. If a similar instant-runoff system were adopted nationwide, Republicans in Vermont would have a strong incentive to swap votes with Democrats in districts where the Democrat was unlikely to win. A similar situation occurred in the 2022 Alaska special election.

Most rated voting systems (including approval voting and score voting) satisfy the favorite betrayal criterion, rendering vote-pairing fully unnecessary. Proportional representation systems also make the practice less important (although it can still occur if there are regionally-calculated electoral thresholds).