The Supplementary Vote

The Supplementary Vote

1. What is it?

   • Used in: London Mayoral Election; all directly elected Mayors; Police and Crime Commissioners in England and Wales
   • The SV is a shortened version of the AV. Under SV, there are two columns on the ballot paper- one for the voters to mark their first choice and one in which to mark a second choice. Voters mark one 'X' in each column, although voters are not required to make a second choice if they do not wish to
     • All the first choices are then counted, and if a candidate has a majority (50%), they are elected. If no candidate receives a majority, the top two candidates continue to a second round and all other candidates are eliminated. The second-choice votes of everyone whose first choice has been eliminated are then counted
       • Any votes for the remaining candidates are then added to their first-round totals. Whichever candidate has the most votes after these second-preferences have been allocated is declared the winner

2. Advantages

   • It is a relatively simple system to understand
   • To some extent, SV encourages conciliatory campaigning, as gaining second-preference votes is important
   • Less safe seats
   • The winning candidate must have secured wide-ranging support; they need not win the first ballot nor will they often have an initial majority of over 50%, but they will need at least some support from across the spectrum to then win the election following the addition of second preference ballots
   • There is only one round of tallying and the process is a little easier to follow than AV, where a candidate might conceivably come third in the first ballot and emerge the winner after several rounds of reallocating second preferences.

3. Disadvantages

   • SV does not eliminate the likelihood of tactical voting
   • The system can lead to a lot of wasted votes as many of the votes cast in the first round end up not transferring and being counted in the second round
   • If there are more than two strong candidates, voters must guess which two will make the final round, and if they guess incorrectly, their second-preference vote will be wasted. In such circumstances it may even be possible for voters to defer their preferred candidate
   • Unlike the AV, SV does not ensure that the winning candidate has the support of at least 50% of the electorate
   • Supplementary Vote encourages a form of strategic voting where the most logical thing to do is to cast your first choice for your genuine favourite candidate, and your second choice for your preferred candidate that you think will reach the top two in the first round.
   • Non-proportional
   • SV strongly promotes voting for only candidates from the main three parties

Images and files in the map