Strengths and weaknesses of different electoral systems in the UKElections to the Scottish Parliament

Additional Member System (AMS) electoral system

The Scottish Parliament uses the Additional Member System (AMS) to elect 129 Members of the Scottish Parliament (MSPs). AMS is a form of proportional representation which means that the overall number of MSPs elected for each party is roughly in proportion with their electoral support.

Video - Additional Member System (AMS)

Watch this video explaining how the Additional Member System (AMS) works.

How does Additional Member System (AMS) work?

AMS is a hybrid electoral system. It provides voters with two votes:

• one for a constituency MSP
• one for a party on a regional list

The constituency MSP is elected as with First Past the Post, ie the person with the most votes wins. There are 73 constituency MSPs.

For the second party list vote, the country is divided into eight regions each returning seven additional MSPs. Regional MSPs are selected from party lists to make the overall result in any one region more fairly reflect each political party's electoral support.

What are the advantages of AMS?

• Proportionality – The percentage of seats won by each party should reflect the percentage of votes received. This is due to the second vote.
• Democratic – No votes are 'wasted' due to the second vote. Even if your chosen candidate isn't elected through the first vote, you are likely to be represented through your second vote.
• Representation – In theory, it may be easier to elect women and people from ethnic minorities if the parties place these people high on their lists in regions where they are likely to gain support.
• Representation - you have a range of MSPs from whom you can seek support. For example, in the West Scotland region, there are MSPs from the SNP, Labour, the Greens and the Conservatives.

What are the disadvantages of AMS?

• Proportionality – AMS is not completely proportional. In 2021, the Liberal Democrats received 6% of the total votes, but only 3% of seats meaning that they are under-represented. The SNP received 44.2% of the vote but 49.6% share of the seats.
• Democratic – The lists are controlled by the parties, so the electorate do not get to choose their representatives directly. This gives the parties considerable power.
• Democratic – AMS is more likely to lead to a coalition government (such as the Labour/Liberal Democrat coalitions from 1999-2003 and 2003-07) or the power-sharing agreement between the SNP and the Greens following the 2021 election. This means that parties may compromise on the election policies that people voted for.
• Participation – there have been issues with spoilt ballot papers, with voters unsure how to use the second ballot paper. In addition, some voters may be confused about which MSP would be best to contact (list or constituency).