additional member system

(AMS)

   A hybrid form of electoral system which combines elements intended to increase proportionality with features of first past the post (FPTP) such as single-member constituencies. There are considerable variations in the possible schemes available, which is why various titles are used such as the ‘mixed member proportional’ or ‘additional member’ systems. Several of the newer Central and Eastern European democracies have opted for these ‘mixed’ systems, which are used in countries as far apart as Hungary and Taiwan. Most varieties involve the voter in making two choices (one for the party and one for the candidate in the individual constituency), but in other respects there is scope for variety. The degree of proportionality will depend upon the split between the constituency and the ‘top up’ list element. In Germany, it is a 50:50 split, in Italy 75:25.

   AMS has been more favourably received in Britain than some other alternative systems, because it retains familiar features such as the link of the elected member to a constituency. It is currently used in the elections for the Scottish Parliament and Welsh National Assembly, as well as for the Greater London Assembly. Scottish nationalists complain that it fails to deliver a fully proportional outcome, for representation in Scottish Parliamentary elections is weighted towards the FPTP constituency element which elects 73 out of 129 members.

   Further reading: D. Farrell, Electoral Systems: A Comparative Introduction, Palgrave, 2001