Mixed-member proportional representation

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Mixed-member proportional representation (MMP or MMPR) is a mixed electoral system which combines local majoritarian elections with a compensatory tier of party list votes, which are used to allocate additional members in a way that aims to produce proportional representation overall. In most MMP systems, voters get two votes: one to decide the representative for their single-seat constituency, and one for a political party. Some countries use single vote variants of MMP, although this article focuses primarily on dual vote versions of MMP.

Seats in the legislature are filled first by the successful constituency candidates, and second, by party candidates based on the percentage of nationwide or region-wide votes that each party received.^[1][2][3] The constituency representatives are usually elected using first-past-the-post voting (FPTP). The nationwide or regional party representatives are, in most jurisdictions, drawn from published party lists, similar to party-list proportional representation. To gain a nationwide representative, parties may be required to achieve a minimum number of constituency seats, a minimum percentage of the nationwide party vote, or both.

MMP differs from parallel voting in that the nationwide seats are allocated to political parties in a compensatory manner in order to achieve proportional election results. Under MMP, two parties that each receive 25% of the votes end up with about 25% of the seats, even if one party wins more constituency seats than the other. Depending on the exact system implemented in a country and the results of a particular election, the proportionality of an election may vary.^[4] Overhang seats may reduce the proportionality of the system, although this can be compensated for by allocating additional party list seats to cover any proportionality gap.^[5]

MMP was first used to elect representatives to the German Bundestag, and has been adopted by New Zealand and others, with modifications.

Other names

In Germany, where it is used on the federal level and in most states, MMP is known as personalized proportional representation (German: personalisiertes Verhältniswahlrecht). This version of MMP produced very proportional election results by a number of additional compensatory seats, known as leveling seats. Germany recently modified their system to not allow overhang seats in a way that not all local districts are guaranteed to elect the plurality winner, thereby eliminating the need for leveling seats also: However due to this revision, the system is no longer considered to be MMP in the sense of a mixed member system combining proportional and majoritarian representation, but a personalized/localized version of PR. As it retains the individual candidate vote in a clearly distinct fashion from open-list systems, it may still be considered mixed-member proportional in the sense of a proportional system having two kinds of MP: one (may be) elected by personal (candidate) votes, one elected by (closed list) votes.

In the

In MMP, the voter casts two votes: one for a constituency representative and one for a party. In the original variant used in Germany, citizens gave only one vote, so that voting for a representative automatically meant also voting for the representative's party, which is still used in some MMP elections today. Most of Germany changed to the two-vote variant to make local members of parliament (MPs) more personally accountable. Voters can thus vote for the local person they prefer for local MP without regard for party affiliation, since the partisan make-up of the legislature is determined only by the party vote. In the 2017 New Zealand election, 27.33% of voters split their vote (voted for a local candidate of a different party than their party vote) compared to 31.64% in 2014.^[9]

In each constituency, the representative is chosen using a

Most systems used closed party lists to elect the non-constituency MPs (also called list MPs). In most jurisdictions, candidates may stand for both a constituency and on a party list (referred to in New Zealand as dual candidacy). In Wales between 2006 and 2014 dual candidacy was banned, i.e. candidates were restricted to contend either for a constituency or for a party list, but not both. If a candidate is on the party list, but wins a constituency seat, they do not receive two seats; they are instead crossed off the party list and the party seat goes to the next candidate down.

In Bavaria, the second vote is not simply for the party but for one of the candidates on the party's regional list: Bavaria uses seven regions for this purpose. A regional open-list method was recommended for the United Kingdom by the Jenkins Commission (where it is known as AMS) and for Canada by the Law Commission of Canada; neither recommendation was ever implemented.

In contrast, the open-list method of MMP was chosen in November 2016 by voters in the 2016 Prince Edward Island electoral reform referendum.

In Baden-Württemberg, there are no lists; they use the "best near-winner" method in a four-region model, where the regional members are the local candidates of the under-represented party in that region who received the most votes in their local constituency without being elected in it (Zweitmandat, literally "second mandate").

The Scandinavian countries have a long history of using both multi-member districts (members elected through party-list PR) and nationally-based compensatory top-up seats using the same method as MMP, however because the local MPs are also elected using PR, these systems are not usually considered MMP as they are not mixed systems.

Apportionment methods

At the regional or national level (i.e. above the constituency level) several different calculation methods have been used, but the basic characteristic of the MMP is that the total number of seats in the assembly, including the single-member seats and not only the party-list ones, are allocated to parties proportionally to the number of votes the party received in the party portion of the ballot. This can be done by different apportionment methods: such as the D'Hondt method or the Sainte-Laguë method. Subtracted from each party's allocation is the number of constituency seats that party won, so that the additional seats are compensatory (top-up).

If a party wins more FPTP seats than the proportional quota received by the party-list vote, these surplus seats are called

Dealing with overhang seats

When a party wins more constituency seats than it would be entitled to from its proportion of (party list) votes, most systems allow for these

In Germany's

won 2.4% of the party vote, which would entitle them to 3 seats in the House, but won 5 constituency seats, leaving an overhang of 2 seats, which resulted in a 122-member house. If the party vote for the Māori Party had been more in proportion with the constituency seats won, there would have been a normal 120-member house.

In most German states, and in the federal Bundestag since 2013, the other parties receive extra seats (leveling seats) to create full proportionality. For example, the provincial parliament (Landtag) of North Rhine Westphalia has, instead of the usual 50% compensatory seats, only 29% unless more are needed to balance overhangs. If a party wins more local seats than its proportion of the total vote justifies, the size of the Landtag increases so that the total outcome is fully proportional to the votes, with other parties receiving additional list seats to achieve proportionality. The leveling seats are added to the normal number of seats for the duration of the electoral period. In the German state of Bavaria, the constituency vote and party vote are combined to determine the distribution of seats.

In one election in Scotland, the

South Wales Central

region apart from the 2003 election. This situation arises because Labour has continued to hold the overwhelming majority of constituency seats in these regions, and only around one-third of the total number of seats are available for distribution as additional regional seats.

Threshold

See also:

Election threshold

As in numerous

proportional systems, in order to be eligible for list seats in many MMP models, a party must earn at least a certain percentage of the total party vote, or no candidates will be elected from the party list. Candidates having won a constituency will still have won their seat. In New Zealand the threshold is 5%, in Bolivia 3%, in Germany 5% for elections for federal parliament and most state parliaments. A party can also be eligible for list seats if it wins at least three constituency seats in Germany, or at least one in New Zealand. Having a member with a 'safe' constituency seat is therefore a tremendous asset to a minor party

in New Zealand.

In elections for the Scottish Parliament and Welsh Assembly, there is no threshold set, because the

district magnitude

of each electoral region is small enough to impose an inherent threshold in the seat distribution calculations.

Countries using MMP

Current and former use

Country	Legislative body	Use	Electoral system		Number of votes (personal and list)	Notes
Albania (formerly)	Parliament (Kuvendi)	2001–2005		Additional member system (AMS) – MMP without levelling seats	Two votes	MMP was used from 2001 to 2005 (after having used parallel voting in the 1996 and 1997 elections).[11][12]
Bolivia	Chamber of Deputies	1994–present		regionalized Additional member system (AMS) – MMP with levelling seats at regional level	Single vote (MSV)	Ballots use a double simultaneous vote with the presidential election[13]
Ethiopia	Tigray State Council	2020		Additional member system (AMS) – MMP without levelling seats	[citation needed]	The General Election was supposed to be held in Ethiopia on 29 August 2020, but they were delayed due to the COVID-19 pandemic.[14] But the government of Tigray dismissed the postponement and decided to create its own electoral commission and hold a regional election. On August 6, 2020, the State Council of Tigray decided to amend its constitution and change the electoral system to MMP, this will affect the upcoming regional elections. The amendment increases the number of seats in the council from 152 to 190 (+38), 80% of the seats will be filled with first-past-the-post voting and the rest 20% by proportional voting.[15] This Tigray National Regional States law is annulled by House of Federation which is empowered to interpret the constitution for violation of the provisions of the constitution of the Federal Democratic Republic of Ethiopia.[16]
Germany	Bundestag (lower house of the federal parliament)	1949–2023[17]		Mixed-member proportional representation (MMP) – with levelling seats	Two votes	Referred to as personalized proportional representation (see electoral system of Germany),[18] in 1949 as a result of inter-party bargaining.[19] Originally used single vote version, switched to two vote version before the 1953 election. Levelling seats were established for the 2013 federal election after a ruling of Federal Constitutional Court, with a minor modification for the 2021 federal election to reduce the size of the Bundestag.
		2023–		Personalized proportional system without overhang seats	Two votes	Germany recently modified their system to not allow overhang seats in a way that not all local districts are guaranteed to elect the plurality winner, thereby eliminating the need for leveling seats also.
	State parliaments , except Bremen, Hamburg Saarland	varies by state		varies by state	varies by state	Bavaria uniquely uses an open-list system for its party-list seats. Baden-Württemberg uses MMP without lists.
Republic of Korea (South Korea)	National Assembly	2019–2024		Supermixed system, includes additional member system (AMS)	Two votes	Modified version of mixed-member proportional as used in the UK, with 253 single-member constituencies, 17 supplementary seats (a la parallel voting), and 30 compensatory seats (AMS)
		2024–present		Additional member system (AMS) – MMP without levelling seats	Two votes
Lesotho	National Assembly	2002–present		Additional member system (AMS) – MMP without levelling seats	Single vote (MSV)	Initially used two vote version, changed to the single vote version in 2012 due to the use of decoy lists.
New Zealand	House of Representatives	1994–present		Mixed-member proportional representation (MMP) – with levelling seats	Two votes	Following a long 1993 referendum on the voting system. It was first used in an election in 1996. The system's use was reviewed by referendum in November 2011, with the majority (56.17%) voting to keep it. In 2020 general election , the Labour Party won 65 out of 120 seats, becoming the first party under MMP to receive a majority.
Romania	Chamber of Deputies	2008–2012		Positive vote transfer system (PVT)	Single vote (MSV)	Local candidates who did not win at least 50% of votes in their districts did not get a direct mandate, but these seats were added to the list seats allocated proportionally. From the 2016 elections, closed party-list proportional representation was used instead.[20]
South Africa	Local elections in all municipalities designated as metropolitan, district/county council (DC) or local/borough council(LC)[21]	[citation needed]		Additional member system (AMS) – MMP without levelling seats	[citation needed]	[citation needed]
Thailand	House of Representatives	2019		Additional member system (AMS) – MMP without levelling seats	Single vote (MSV)	Referred to as "mixed-member apportionment", uses a mixed single vote for both the constituency and the party list. The 350 constituency seats are won by first-past-the-post voting as in previous elections. However, the 150 party-list seats serve a compensatory function, and are allocated so as to give each party a total number of seats proportional to the nationwide number of votes they received (top-up).[22][23][24][25] The next elections are again set to be held under parallel voting due to a change in the constitution.[26]
United Kingdom	Scotland - Scottish Parliament	[citation needed]		Additional member system (AMS) – MMP without levelling seats	Two votes[citation needed]	MMP with each electoral region normally electing 9 local MSPs (with exceptions to 3 regions) and 7 regional MSPs
	Senedd (Welsh Parliament)	[citation needed]		Additional member system (AMS) – MMP without levelling seats	Two votes[citation needed]	MMP with each electoral region normally electing 8 local MSs (with exceptions to 2 regions) and 4 regional MSs.
	Local elections in London (Assembly)	[citation needed]		Additional member system (AMS) – MMP without levelling seats	Two votes[citation needed]
Venezuela	National Assembly	?–2009[citation needed]		Additional member system (AMS) – MMP without levelling seats	Two votes	The link between list and constituency representatives was removed in 2009, which changed the system to parallel voting.[citation needed]

Proposals for use

Canada

In March 2004, the Law Commission of Canada proposed a system of MMP,^[27] with only 33% of MPs elected from regional open lists, for the House of Commons of Canada^[28] but Parliament's consideration of the Report in 2004–5 was stopped after the 2006 election.

The New Democratic Party has been a longtime supporter of MMP. The Green Party of Canada has generally been a staunch supporter of a move to a proportional electoral system.

A proposal to adopt MMP with closed province-wide lists for elections to the Legislative Assembly of Prince Edward Island was defeated in a referendum in 2005, and in a subsequent referendum in 2019.

In 2007, the

provincial election on 10 October 2007, saw it defeated.^[29]

In June 2016, the Canadian House of Commons Special Committee on Electoral Reform was formed to examine potential changes to the voting system with MMP being one of the options examined. The committee presented its report to Parliament on 1 December of the same year. In early 2017, the Government announced that it would accept only some of the committee's recommendations, and would not pursue the issue of electoral reform any further.^[30][31]

In a non-binding plebiscite between 27 October and 7 November 2016, Prince Edward Islanders voted for MMP over FPTP in the final round of counting, 52%–43%; however, the provincial government, despite having set no voter turnout threshold, subsequently claimed that the 36 percent turnout was insufficient to change the electoral system.^[32] A second referendum, held simultaneously with the provincial election, saw MMP rejected by a margin of 48% in favor to 52% against, with 76% turnout.

During October–December 2018,

British Columbia New Democratic Party who took office following the May 2017 provincial election. In the referendum citizens were presented with two questions. The first question asked them to choose whether they would like to keep first-past-the-post voting or change to proportional representation. The second question asked them to rank three types of proportional voting systems in order of preference; one of those was MMP.^[34] Citizens could still rank the voting systems even if they selected first-past-the-post voting

in the first question. According to official results, voters chose FPTP over PR by 61.3% to 38.7% on the first question. While the first question was not successful for PR, the second question resulted in MMP winning over the two other systems on the ballot. If PR had been successful on the first question, MMP would have been adopted in time for the next provincial election and would have been subject to a second referendum after two election cycles.

In September 2019, Quebec's government, supported by two of the three opposition parties (PQ and Quebec Solidaire), introduced a

referendum on MMP to be held in 2022. However, On April 28, 2021, Justice Minister Sonia LeBel informed a legislative committee hearing that the government would not move forward with a referendum on electoral reform in 2022. LeBel blamed the COVID-19 pandemic for altering the government's timeline and could not or would not commit to providing an alternate date for the referendum, effectively ending discussions about electoral reform in Quebec.^[35]

Costa Rica

Currently Costa Rica was debating the switch from the current

First pass the post basis.^[36] As the bill requires a constitutional reform it would require a two-thirds majority of votes, however as of 2019 the caucuses of the four main parties support the reform.^[37]

European Union (European Parliament)

The pan-European party VOLT Europa proposes transnational mixed-member proportional representation with the combination of Majority Judgment and party-list PR.^[38]

Sri Lanka

In September 2015, Sri Lankan Foreign Minister Mangala Samaraweera announced that they will change the country's system to MMP.^[39]

South Africa

In South Africa, MMP is generally referred to as a "mixed-system". The Van Zyl Slabbert Commission on Electoral Reform (published in January 2003)^[40] recommended that a multi-member system, which has been adopted for municipal elections, be expanded to elections for the National Assembly. It proposed that 300 of 400 members be elected from closed-constituency lists (from 69 national multi-member constituencies) and 100 members from closed, national-level party lists. Parliament's High Level Panel report of 2017, chaired by former president Kgalema Motlanthe, validated the Van Zyl Slabbert mixed-system and recommended its adoption, stating: "Such a system will serve to limit the power of individual party leaders and encourage MPs to vote in accordance with the needs and desires of their constituencies rather than only following party lines".^[41] Although a constitutional amendment is not required, and a simple majority in parliament can amend the Electoral Act (No. 73 of 1998) it seems unlikely that such an amendment will come before parliament before the 2019 General Elections. A former MP, Michael Louis, who wishes to stand as an independent, is actively pursuing a judicial route to force an amendment.^[42] The Independent Electoral Commission (IEC) has stated that it is not opposed to an amendment but there is simply not enough time to implement it in time for the 2019 elections.

After the

Valli Moosa

-led ministerial advisory committee was formed to determine the new system.

Tactical manipulation

Split ticket voting

In other cases, a party may be so certain of winning a large number of constituency seats that it expects no extra seats in the proportional top-up (list seats). Some voters may therefore seek to achieve double representation by voting tactically for another party in the regional vote, as a vote for their preferred party in the regional vote would be wasted. This tactic is much less effective in MMP models with a relatively large share of list seats (50% in most German states, and 40% in the New Zealand House of Representatives) and/or ones which add "balancing seats", leading to fewer opportunities for overhangs and maintaining full proportionality, even when a party wins too many constituency seats.

Solutions

The problem of ticket splitting strategies can be solved either by eliminating at least one of the two mechanism that create the opportunity for abuse: Either the double vote can be abolished, returning to a mixed single vote (the original version of MMP used in Germany), in which case voters cannot split their ticket, even if it is a sincere preference. Another solution is to eliminate the seat linkage mechanism and use a vote linkage one instead, in which case most likely more compensatory seats would be needed.^[5] A negative vote transfer based system (scorporo) retains the flaw that decoy lists can be used to abuse it, but if the two votes were tied in a mixed ballot transferable vote, the potential this kind of strategic manipulation would be eliminated. However, in this a case party proportionality is not likely and overall equality of votes would depend largely on the specifics of the system (the amount of compensation).

Compensatory mixed systems
	single vote systems	dual vote systems
Seat linkage	mixed single vote, top-up versions (MSV) single vote MMP single vote AMS (Bolivia, Lesotho)	mixed-member proportional representation (MMP)
		additional member system (AMS)
		alternative vote plus (AV+)
		Hybrids: e.g. parallel voting+AMS (South Korea)
Vote linkage	positive vote transfer (PVT/MSV) Hungarian PVT/MSV (local elections) Romanian PVT/MSV system (2008-2012)	Hybrids: Parallel voting+PVT (Hungary) negative vote transfer/scorporo (Italy, 1993-2005)
	Others systems:
	dual-member proportional (DMP)	mixed ballot transferable vote (MBTV)

Splitting parties

It has been suggested that this section be split out into another article. (Discuss) (March 2024)

This sort of strategy for a coalition of parties to capture a larger share of list seats may be adopted formally as a strategy. By way of example, in

In an abusive gambit similar to that used in Albania, major parties feeling that they are unlikely to win a large number of list seats because of their advantage at the constituency level might choose to split their party in two, with one subdivision of the party contesting the constituency seats, while the other contests the list seats—assuming this is allowed by electoral law. The two linked parties could then co-ordinate their campaign and work together within the legislature, while remaining legally separate entities. The result of this approach, if it is used by all parties, would be to transform MMP into a de facto parallel voting mechanism.

An example of how this could happen manifested itself in the 2007 Lesotho general election. In this case the two leading parties, the Lesotho Congress for Democracy (LCD) and the All Basotho Convention (ABC) used decoy lists, respectively named the National Independent Party and the Lesotho Workers' Party to avoid the compensatory mechanisms of MMP. As a result, the LCD and its decoy were able to take 69.1% of the seats with only 51.8% of the vote. ABC leader Tom Thabane called the vote "free, but not fair." In the 2012 election, the voting system was adjusted to link the local and list seats to limit the decoy lists' effectiveness, resulting in an almost perfectly proportionate election result for the competing parties.^[44]

Another interesting case is that of Venezuela, which also ended up changing its system, in this case by formally adopting a parallel voting system and legitimizing party efforts to game the MMP approach. Venezuela introduced an MMP

Another example is that of the 2001 Italian general election, in which one of the two main coalitions (the House of Freedoms), which opposed the scorporo system (a system compensatory system similar to MMP), linked many of their constituency candidates to a decoy list (liste civetta) in the proportional parts, under the name Abolizione Scorporo. As a defensive move, the other coalition, Olive Tree, felt obliged to do the same, under the name Paese Nuovo. This meant that the constituency seats won by each coalition would not reduce the number of list seats available to them. In the case the House of Freedoms list faction Forza Italia, the tactic was so successful that it did not have enough candidates in the proportional part to receive as many seats as it in fact won, missing out on 12 seats. Italy subsequently changed its system.

Ahead of the 2020 South Korean legislative election, the electoral system was changed from parallel voting to a hybrid mixed-member proportional system, with 30 seats allocated in a compensatory manner. The opposition Liberty Korea Party subsequently set up a decoy list, the Future Korea Party, to win extra proportional seats.^[45] The ruling Democratic Party of Korea condemned them for exploiting the electoral law, but nonetheless set up its own decoy list, the Platform Party, in response.^[46] The decoy lists were successful on election day, with Future Korea winning 12 compensatory seats and Platform winning 11. After the election, both decoy lists merged into their mother parties.

Electoral thresholds

In systems with a threshold, people who prefer a larger party may

Similarly, in New Zealand, some voters who preferred a large party have voted for the minor party's local candidate to ensure it qualifies for list seats on the back of winning a single electorate. This notably occurred in the right-wing inner Auckland electorate of Epsom in 2008 and 2011, where the National Party voters gave their local vote to the ACT Party. In this case the tactic maintained some proportionality by bypassing the 5% threshold, but is largely disfavoured by the public due to it awarding smaller parties extra list seats while parties with a higher party vote percentage that do not win an electorate receive no seats; this occurred in 2008 when ACT was awarded 5 seats on the back of one electorate seat and 3.7% of the party vote, while New Zealand First with no electorate seats and 4.1% of the party vote were awarded none. In 2011, some Epsom voters voting for the left-wing Labour and Green parties tried to block the tactic by giving their local vote to the National candidate; while it was unsuccessful, it did reduce ACT's majority over National from 12,900 to 2,300. In August 2012, the initial report on a review of the MMP system by the Electoral Commission recommended abolishing the one electorate seat threshold, meaning a party winning an electorate seat but not crossing the 5% threshold (which the same report recommends lowering to 4%) is only awarded that electorate seat.^[47]

See also

• Additional member system
  , MMP as implemented in the United Kingdom
• Alternative Vote Plus
• Leveling seat
• Mixed single vote
• Mixed ballot transferable vote
• Dual-member proportional
• Biproportional apportionment

References

Notes