Single non-transferable vote

Three seats are to be filled among five candidates: A, B, C, D and E fielded by 3 parties X, Y and Z.

C, D and E are the winning candidates. Thus, Party Z gets two seats and Party Y gets one seat. No one party took all the seats as might have been the result under first past the post or plurality block voting.

But counting the votes by party gives these vote tallies:

Party Y has more votes than Party Z, but receives fewer seats because of an inefficient spread of votes across the candidates. If Party Y's two candidates had had more equal vote tallies, it would have won two seats and Party Z only one. Or if Party Z's candidates had received less equal vote tallies, Party Y would have won two seats even if its candidates were not equally popular. (There is more chance in SNTV than a more orderly system of PR.)

If either party had risked trying to win all three seats, causing more vote splitting among supporters of Parties Y and Z, then A of Party X might have won a seat and either party Y or Z would then have taken one fewer seat.

Candidates are running in a 3-member district of 10000 voters. Under non-transferable (and non-cumulative) voting, voters may not cast a more than one vote for a single candidate.

• Under block voting, the standard multiple non-transferable vote, voters may cast 3 votes (but do not have to)
• Under Limited voting, voters may cast 2 votes maximum.
• Under the single non-transferable vote, voters may cast 1 vote.

Party A has about 35% support among the electorate (with one particularly well-liked candidate), Party B around 25% (with two well-liked candidates) and the remaining voters primarily support independent candidates, but mostly lean towards party B if they have to choose between the two parties. All voters vote sincerely; there is no tactical voting. Percent of votes under MNTV and Limited Voting is the percent of voters who voted for the candidate, not the percent of votes cast.

• Single non-transferable vote described here is not a type of approval voting.
• The three most popular candidates according to voters' first preferences are elected, regardless of party affiliation.
• Under block voting (Plurality block voting), the three candidates of the most popular party are elected if its supporters vote along party lines. In this case a party with only 35 percent support took all the seats.
• Under limited voting, it is most likely that the party with a plurality takes two seats (or the same number of seats as the number of votes each voter has), and another less-popular party receives the remaining seat(s).
• Under the single non-transferable vote (like in the other two methods) the number of seats are sometimes not proportionately allocated. Over-optimism (running too many candidates) and vote splitting is harshly punished. But each popular party that runs one candidate is assured of success to that degree anyway. In this case, even though the most-popular party ran three and risked vote splitting, it did elect one member.
• STV (not shown here) would see each party take its due share of seats if voters mark their preferences along party lines. Thus Party A and Party B would take one seat for sure, with the other seat going to Party B due to it being the choice of supporters of the lesser parties if it came to choice of those two main parties.

In Puerto Rico, where SNTV is known as at-large representation ("representación por acumulación" in Spanish), political parties vary the ballot order of their candidates across electoral divisions, in order to ensure each candidate has a roughly equal chance of success. Since most voters choose the candidates placed at the top of their party lists on their ballots, at-large candidates from the same party usually obtain approximately equal vote totals.

The two major Puerto Rican political parties, the Popular Democratic Party and the New Progressive Party, usually nominate six candidates for each chamber, while the much smaller Puerto Rican Independence Party runs single-candidate slates for both the Senate and the House of Representatives. The overall distribution of legislative seats is largely determined by the results for the sixteen Senate and forty House district seats, elected by plurality voting.

SNTV was once used to elect the legislatures of Japan, South Korea and the Republic of China (Taiwan), but its use has been discontinued for the most part. It is still used in Japan for some seats in the House of Councillors (Sangi-in), prefectural assemblies and municipal assemblies.

In Taiwan it is used for the six aboriginal seats in the Legislative Yuan (national legislature), as well as local assemblies. The party structure there was complicated by the fact that while members of the Legislative Yuan were elected by SNTV, executive positions were (and still are) elected by a first past the post. This created a party system in which smaller factionalized parties, which SNTV promotes, have formed two large coalitions that resembles the two party system which first past the post rewards. Starting with the 2008 legislative elections, SNTV was discarded in favor of a mixed single member district (SMD) with proportional representation based on national party votes, similar to Japan. This system was a legacy of its colonial rule inherited from the Meiji Constitution.[12]

From 1997 to 2016, the electoral system for up to half of the seats of the Legislative Council of the territory was nominally a party-list proportional representation system with Hare quota. In practice, political parties fielded multiple lists in the same constituency. For example, the Democratic Party fielded three separate lists in the eight-seat New Territories West constituency in the 2008 election, aiming to win three seats (they won two). Split list or split tickets is done in order to win more seats with fewer votes, since the first candidate on each list would require less than the Hare quota to get a seat. Supporters are asked to split their votes among the lists of the same party, usually along geographical location of residence. In the 2012 and 2016 elections, no candidate list won more than one seat in any of the six PR constituencies which returned a total of 40 seats, rendering the result effectively the same as SNTV.

In the 2021 Hong Kong electoral reform, the Standing Committee of the National People's Congress instituted SNTV in its amendment to Annex 2 of the Basic Law on 30 March 2021.[13] 20 seats of the Legislative Council are returned by geographical constituencies (GC) through single non-transferable vote with a district magnitude of 2. Effect of the district size of 2 under SNTV system in Hong Kong have been compared to that of the binomial voting system.[14]

In accordance with its post-Gadaffi electoral law, Libya in 2012 elected 80 members of its 200-seat General National Congress using single non-transferable vote.[15] Some commentators cited the system as a factor in the subsequent return to civil war in 2014.[16]

After the 2015 electoral reform, Chileans elect their representatives to both houses of Congress through open lists presented by parties or party coalitions in each of the electoral districts into which the country is divided for the contest, allowing only one vote for one of the candidates inside any list. Once the voting is over, the distribution of seats in each district (which can range from 3 to 8 in the lower house and from 2 to 5 in the upper one) is carried out through the D'Hondt method, ordering the lists from highest to lowest according to the total vote of each one and the candidates within each one of them with the same principle.[17]

SNTV was used in Jordan from 1993 to 2016. SNTV became the official electoral system for legislature elections in Jordan in 1993, the second election since the country's return to an elected parliament in 1989. The 1993 electoral reform introduced SNTV as the "one-man, one-vote", which was argued to be a more egalitarian alternative to the former "block vote" (or Multiple non-transferable vote) where constituents could cast as many votes as there were seats in their constituency. (Under SNTV, each voter cast just one.) The Jordanian opposition parties were heavily critical of the voting reform as it significantly hurt their electoral results. The Islamic Action Front was at the forefront of this criticism, boycotting 4 of the 6 elections held under this system. The last election held purely under this system was in 2010, whose parliament was dissolved after the Arab Spring protests in Jordan and a new election was held in 2013 using both SNTV and a national closed list with a proportional system. SNTV was completely abolished after the 2016 electoral reform where it was replaced with open list PR (in 23 constituencies of between three and nine seats each) plus 15 seats reserved for women.

Kuwait has used SNTV to elect the members of its National Assembly (Majles al-Umma) in five 10-member districts, starting with the 2012 election.[18]

Since independence from Britain and France in 1980, Vanuatu has used SNTV to elect most of the members of its Parliament. Currently, other than eight members elected in single-member constituencies, the 52 members of Parliament are elected in ten multi-member constituencies (of between two and seven seats) by single non-transferable vote. The last election this was done was the 2020 Vanuatuan general election.