Mixed Member Proportional (MMP)

Under MMP systems, the PR seats are awarded to compensate for any disproportionality produced by the district seat results. For example, if one party wins 10 per cent of the vote nationally but no district seats, then it will be awarded enough seats from the PR lists to bring its representation up to 10 per cent of the seats in the legislature. Voters may get two separate choices, as in Germany and New Zealand. Alternatively, voters may make only one choice, with the party totals being derived from the totals for the individual district candidates.

The proportion of seats allocated according to the two elements of the system vary from country to country. Lesotho’s post-conflict electoral system contains 80 FPTP seats and 40 compensatory ones while Germany elects 299 candidates under each system.

Although MMP is designed to produce proportional results, it is possible that the disproportionality in the single-member district results is so great that the list seats cannot fully compensate for it. This is more likely when the PR electoral districts are defined not at national level but at regional or provincial level. A party can then win more plurality/majority seats in a region or province than its party vote in the region would entitle it to. To deal with this, proportionality can be closely approached if the size of the legislature is slightly increased: the extra seats are called overhang mandates or Überhangsmandaten. This has occurred in most elections in Germany and is also possible in New Zealand. In Lesotho, by contrast, the size of the legislature is fixed, and the results of the first MMP election in 2002 were not fully proportional.

Advantages and Disadvantages of MMP

While MMP retains the proportionality benefits of PR systems, it also ensures that elected representatives are linked to geographical districts. However, where voters have two votes—one for the party and one for their local representative—it is not always understood that the vote for the local representative is less important than the party vote in determining the overall allocation of seats in the legislature. Furthermore, MMP can create two classes of legislators—one group primarily responsible and beholden to a constituency, and another from the national party list without geographical ties and beholden to the party. This may have implications for the cohesiveness of groups of elected party representatives.

In translating votes into seats, MMP can be as proportional an electoral system as pure List PR, and therefore shares many of the previously cited advantages and disadvantages of PR. However, one reason why MMP is sometimes seen as less preferable than straight List PR is that it can give rise to what are called ‘strategic voting’ anomalies. In New Zealand in 1996, in the constituency of Wellington Central, some National Party strategists urged voters not to vote for the National Party candidate because they had calculated that under MMP his election would not give the National Party another seat but simply replace an MP who would be elected from their party list. It was therefore better for the National Party to see a candidate elected from another party, providing that candidate was in sympathy with the National Party’s ideas and ideology, than for votes to be ‘wasted’ in support of their own candidate.