SM vs MMP

The Weekend Herald reports as saying he does not favour a return to , but is leanign towards which is a semi-proportional system.

“I’m leaning towards Supplementary Member,” Mr Key said. “It allows for proportionality while ensuring it’s not the dominating factor. You get the best of without it being overpowering. That is the reason why.”

I also don’t support a return to FPP, but think both STV and SM have merit. MMP has worked well in many ways, but there are areas where it does not. I think the biggest weakness is the huge power given to so called centrist politicians such as Peters. There is no doubt he would have been sacked from his Ministerial role by now, if it were not for MMP.

For those who do not know how SM works, it is very similar to MMP but with the vital change that the allocation of list MPs is done by having them supplementary to the electorate MPs. In practical terms it means that under SM every electorate won by a party is a net gain for thet party. Under MMP if you win an additional electorate, you get allocated one less list MP.

SM is used in around 16 countries including Japan, Georgia, South Korea, and Taiwan.

Anyway it is worth taking a look at SM, the pros and cons of it. No electoral system is perfect with only positive attributes. So what are the pros and cons of SM:

Pros of SM

  1. Could not be simpler to implement – the only change is how List MPs are allocated by the Chief Electoral Officer.
  2. Retains party lists, allowing parties to use them to have more diverse MPs
  3. Minor parties who make 5% retain a presence in Parliament
  4. Reduces the “tail wagging the dog” syndrome where minor parties gain power massively in excess of their share of the vote
  5. Makes it less likely you will need as many as four parties to form a Government
  6. Increases the chance the Government will be known on election night, and not decided by who is the best negotiator
  7. Will make Government less able to ignore the public mood on controversial issues such as anti-smacking bill, as losing electorate seats is far more devastating under SM than MMP.
  8. Would be safer to reduce the threshold for representation from 5%, as minor parties less powerful
  9. Unlike FPP, every vote will still count towards gaining more MPs for your party
  10. Removes the problem of over-hang (ironically by sort of making every electorate seat an over-hang seat)

Cons of SM

  1. Is only a semi-proportional system, therefore one could end up with a situation where a Government received less votes than the Opposition. This is also possible under MMP with overhang. Under SM it is more likely than under MMP but less likely than under FPP.
  2. Increases the chance a party can form a Government by itself (some will say this is a pro)
  3. Encourages pork barrel politics as marginal seats become far far more important under SM than under MMP
  4. Favours parties which can win electorate seats
  5. Over time electorates would grow in importance as number of List MPs declines – unless the size of Parliament as a whole grows, or the number of electorate seats is frozen.

There are probably more pros and cons that these ones. Feel free to add them below.

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