Mixed Member Proportional Voting System Explained | Electoral Reform Canada

There are three types of party lists: (1) Open lists - voters can choose individual candidates, and candidates with more votes win seats (Brazil uses this system); (2) Closed lists - voters choose parties, and parties determine seat allocation based on their vote share; (3) Semi-open lists - voters can choose parties but can also indicate preferences for specific candidates. Brazil is the largest country in the world using open lists, and Chile and Finland also use this system.

Votes and seats don't divide neatly, requiring mathematical formulas for fair allocation. The D'Hondt formula, developed by Belgian mathematician Victor D'Hondt, solves this through successive division. Steps: divide all votes by 1, find highest quotient to assign first seat, add 1 to that party's divisor, repeat until all seats filled. With 10 seats, Brexit Party gets 3, Labour 3, Lib Dems 2, Conservatives 1, Greens 1—roughly matching vote percentages. This ensures proportional allocation while handling the integer constraint of whole seats.

Closed lists allow only party voting, with candidates elected in their original list order regardless of individual popularity. Open lists permit preferential voting, where candidates are elected based on individual vote counts regardless of list position. Before the 2003 reform, the cociente and residuo system led to 'Operation Avispa,' where parties created multiple lists to maximize seat allocation through remainders. A party with 300,000 votes and a quota of 100,000 would receive 3 seats, but by creating 10 lists with 30,000 votes each, they could gain 10 seats through remainders. This strategic manipulation undermined fair representation and prompted the 2003 reform.

The closed list system is a pre-determined candidate list prepared by parties before elections, submitted to the Election Commission with no changes allowed afterward. Lists must reflect demographic quotas for different ethnic communities and include at least 50% women. The 3% national threshold acts as a filter, excluding parties below this percentage from seat allocation. Seat allocation uses a mathematical formula: total votes from qualifying parties are divided by 110 (the number of proportional seats) to determine the value of one seat. Each party's votes are then divided by this seat value to determine their seat allocation. For example, with 1 million total votes and 110 seats, each seat is worth approximately 9,090 votes.

Proportional representation with open lists operates through a multi-stage allocation process. First, a threshold quota is calculated by dividing total voters by total mandates (e.g., 1 million voters ÷ 18 mandates = 55,555 votes per seat). Candidates meeting or exceeding this threshold automatically win seats. Second, remaining seats are allocated proportionally using the D'Hondt method, which divides each party's total votes by sequential integers (1, 2, 3...) and assigns seats to the highest quotients. This ensures both individual candidate accountability and overall proportionality, with additional seats going to the strongest performers rather than predetermined list positions.

Several countries have attempted electoral reform while others maintain FPTP. The UK Jenkins Commission examined alternatives in the late 1990s, and a 2011 referendum rejected the alternative vote system 2-to-1. Canada's British Columbia failed to adopt STV in 2005 (57% approval, 60% threshold). Ontario's 2007 mixed member proportional referendum failed with 36.9% support. Proponents of ranked voting systems argue they reduce tactical voting and better capture voter preferences. The debate reflects ongoing tensions between simplicity, proportionality, and democratic representation in electoral design.

The Alternative Vote (AV) System, used in Australia and for Indian Vice Presidential elections, allows voters to rank candidates in order of preference. The candidate who receives more than 50% of first-preference votes wins. If no candidate achieves this, the candidate with the fewest votes is eliminated and their votes are redistributed according to voters' next preferences. This process continues until a candidate achieves a majority. The Single Transferable Vote (STV) System, used in Ireland and Northern Ireland, is a proportional representation method that allows multiple candidates to be elected from a single constituency. Voters rank candidates, and seats are allocated based on a quota system calculated by dividing total votes by seats plus one. Candidates reaching the quota are elected, and their surplus votes are transferred to other candidates.

The Single Transferable Vote (STV) is an electoral system where voters rank candidates in order of preference (1st, 2nd, 3rd, etc.) rather than selecting a single candidate. Seats are allocated based on a quota (typically calculated as total votes divided by seats plus one), with surplus votes from winning candidates transferred to voters' next preferences, and votes from eliminated candidates redistributed. This system ensures votes are not wasted, prevents large parties from dominating with minority support, maintains local representation, and allows voters to support candidates from different parties across their preference rankings.

Single Transferable Vote (STV) is a proportional system used in multi-member constituencies where voters rank candidates. Candidates are elected based on quotas, with surplus votes transferred according to preferences. This maximizes voter choice by allowing votes for specific individuals rather than just parties. Additional Member System (AMS) combines FPTP with party lists, distributing additional seats to ensure proportionality. It is used in Welsh Senedd and Scottish Parliament. The French two-round system uses single-member constituencies with runoff elections. Any party receiving more than 15% advances to the second round, forcing parties to negotiate alliances and stand down in certain constituencies. Different electoral systems prioritize different values: party list maximizes proportionality but eliminates local representation; STV balances proportionality, local representation, and voter choice; Additional Member System provides proportionality while maintaining single-member districts; Alternative Vote keeps majoritarianism but eliminates FPTP randomness.

The Alternative Vote System (Ranked Voting) allows voters to rank candidates in order of preference. If no candidate receives a majority of first-preference votes, the candidate with the fewest votes is eliminated, and their votes are redistributed according to next preferences. This process continues until a candidate achieves a majority. The Single Transferable Vote (STV) System is based on percentage rather than absolute vote counts, with votes transferred between candidates based on preferences. This system is used for elections with multiple candidates per constituency, such as presidential elections in India.

New Zealand's 2017 general election demonstrated how the Mixed-Member Proportional (MMP) electoral system creates complex coalition politics, where voters cast two votes—one for an electorate representative and one for a political party—to determine both individual representation and proportional parliamentary composition; this system, combined with a 5% threshold for party entry and overhang seats when parties win more electorates than their party vote entitles them to, resulted in a historic tight race where Labour increased its seats while National maintained power through a coalition with New Zealand First, illustrating how MMP enables smaller parties to become kingmakers despite having minimal overall support.

A concern is that PR compromises local representation, but MMP systems like Germany's guarantee half seats are local. Research shows few people actually know their local member, and voter turnout drops when parties are absent. Single-member plurality encourages polarization because parties compete for median voters. PR can reduce polarization because parties must appeal to broader coalitions to form governments, though this requires compromise. PR systems producing coalition governments enable longer-term planning because coalition partners have incentives to work together across election cycles. Single-member plurality systems may pursue short-term policies maximizing electoral advantage, leading to 'policy lurch' where policies reverse with each government change.

In New Zealand's MMP electoral system, coalition governments require negotiation and compromise between parties, which can slow decision-making but also provides checks on power; the recent government push-back against iwi/council co-governance agreements demonstrates how coalition partners (National Party, ACT, and New Zealand First) can collectively resist policies that would institutionalize minority influence, showing that MMP's multi-party dynamics can protect democratic principles even when individual parties might otherwise pursue such policies.

New Zealand's Mixed Member Proportional (MMP) electoral system requires parties to achieve either 5% of the party vote or win an electorate seat to enter Parliament, enabling multi-party representation while guaranteeing local representation through electorate votes; this system was demonstrated in the 2020 general election where Jacinda Ardern's Labour Party achieved a historic 64-seat majority (49.1% party vote) without needing coalition partners, defeating Judith Collins' National Party (26.8% party vote) amid the pandemic, with minor parties ACT (8%) and the Greens (7.6%) crossing the threshold to gain parliamentary representation.

Mixed Member Proportional (MMP) electoral reform, implemented in New Zealand in 1996, was designed to make Parliament more representative of New Zealand society by ensuring it looks like the country itself, with both electorate MPs (who campaign door-to-door and are grounded in their constituencies) and list MPs contributing to diverse representation; however, the system has paradoxically strengthened party discipline, limiting MPs' ability to represent their individual consciences on issues like cannabis legalization and euthanasia, as breaking rank publicly attracts media attention while undermining party unity and effective governance.