additionalmember

Additional member refers to a representative elected under an additional-member seat in certain hybrid electoral systems that combine first-past-the-post constituencies with regional party lists. In these systems, voters typically cast two ballots: one for a local constituency member and a second for a political party in larger regional districts. Constituency winners are elected by first-past-the-post, while additional members are drawn from party lists to achieve broader proportionality in the region.

The purpose of the additional member is to balance the number of seats a party receives with its overall level of support, reducing the distortion that can come from a purely plurality-based system. Regional seats are allocated using a formula such as the d’Hondt method, taking into account the number of constituency seats already won by each party. This mechanism helps ensure that the total number of seats a party holds in a region more closely reflects its share of the second votes.

Notable implementations of the additional-member concept are in the Scottish Parliament and the Welsh Senedd, where the system is designed to preserve local representation while improving overall proportionality. Other jurisdictions have used or adapted similar mixed systems with additional-member seats.

Advantages of this approach include increased proportionality, reduced wasted votes, and preserved constituency representation. Critics point to added complexity, potential conflicts of accountability between constituency and regional members, and, in some designs, the possibility of overhang or the need for balancing seats to maintain proportionality. Overall, the additional member plays a key role in balancing local ties with fairer reflection of voters’ preferences.