1.3 – Electoral systems
On Monday 13 April, the Democratic Unionist Party (DUP) announced that Julie Middleton would be co-opted to fill the vacancy caused by the resignation of her husband from the Foyle constituency in the Northern Ireland Assembly, the thirteenth such co-option since the 2022 Assembly election.
The co-option system allows parties to replace MLAs who die or resign from the Assembly, without the need for a by-election, thereby ensuring the party balance remains the same. This is particularly important in a deeply divided society, such as Northern Ireland, where one community might be large enough to merit representation, but would never be able to win outright. Foyle serves as a good example of this – with its overwhelmingly Catholic (and nationalist) population, the DUP would have no chance of retaining this seat in a by-election. However, the party has won one of the five seats (previously six) in the Assembly at every election since 1998, and co-option ensures that the minority unionist population will retain its representation.
Whilst co-option has its advantages in situations like the one in Foyle, it is also open to abuse. The number of co-options has increased significantly since 2011, peaking in the sixth Assembly (2017-22) when there were 29 co-options – accounting for almost one-third of members. With MLAs safe in the knowledge that their party will retain their seat, they appear to be more willing to vacate office than might be the case at Westminster, where a vacancy will always trigger a by-election. Larger parties have also been known to have members who do not intend to run again vacate their seats early to help their replacement gain wider exposure ahead of the election.
It can be argued, therefore, that whilst STV has the advantage of allowing smaller parties to gain representation without needing to poll a plurality of votes, there is an inherent weakness in the system when it comes to filling vacancies – either that smaller parties are disadvantaged in by-elections, or a co-option system is used which may then raise questions about the legitimacy of co-opted members.