In New Zealand’s MMP system, there are by-elections if there is a vacancy between general elections in a single-seat district. This is not a mandatory feature of MMP systems; Germany, for example, has no by-elections. A vacancy in a district is filled off the list of the party of the vacating member.
Nigel Roberts, a leading New Zealand expert on elections and electoral systems, writes in the Dominion Post that New Zealand should end the practice of by-elections. In making the case, he refers to a by-election in the constituency of Mt Albert, which is a safe Labour seat. The Labour Party’s candidate in the by-election, Jacinda Ardern, already is an MP, via the party list. Thus the effect of her winning (which she did) is simply to shift the type of mandate she has*, and have her replaced as a list MP by the next available candidate on the Labour list from the preceding election.
Roberts suggests adding a regional component to the lists in order to ensure that the replacement is from the same region as the district in which the vacancy has occurred.
A potential problem with the proposal is the fact that sometimes a by-election really does shift who controls a district and sometimes can even change the nationwide balance between parties (as happened in a recent case in Northland district). Roberts takes the position that this is better avoided, so as not to change potentially the majority for the government. “Party votes cast in general elections should make or break governments – not electorate votes cast in by-elections,” he says.
I am curious to know what readers think of the proposal.
* As well as, sadly, deprive us of my favorite case of a list MP “shadowing” the district-elected MP.