Scottish voters have become used to using several voting systems over the past few years, with the traditional "first past the post" system still in use for Westminster elections and two different versions of proportional representation (the additional members system and the party list system) used for elections to the Scottish Parliament and the European Parliament respectively. However, as Scottish voters head for polling stations on 3rd May, it will be the first time that Scotland has had four voting systems in operation. The new system, known as the Single Transferable Vote, will be used for Local Authority elections. This article looks at the advantages and disadvantages of such a system. The introduction of various methods of proportional representation in Scotland could be seen as a response to the failings of the traditional first past the post (FPTP) system. The new Single Transferable Vote system (STV) being introduced for the Scottish local government elections, is already used in Northern Ireland, as well as in Australia and Malta. It requires voters to rank candidates in order of preference, choosing as many or as few candidates as they like. If the voter's first choice already has enough votes to be elected, the vote is transferred to the second choice and so on. Similarly, if a voter's first choice candidate has very few votes, far too few to be elected, then the voter's vote for that candidate will be discounted and its second choice vote used instead (and so on with third and fourth choices etc). In order for STV to operate effectively, the size of the wards has been increased and three or four candidates will be elected from each ward.

STV is often viewed as being one of the most complex of proportional representation systems, so why was it chosen? Primarily it was because the system can be said to reduce the number of "wasted" votes. FPTP uses the "one person, one vote" principle and has long been criticised for unfairly representing the overall voting pattern. For example, in the 2005 General Election, only three MPs gained the votes of more than 40% of their constituents (all figures are from the Electoral Reform Society Scotland), with the result that a large percentage of votes are effectively wasted as they were not taken account of at all. With a STV system, few votes are wasted and representation is improved, with the need for tactical voting greatly reduced. It can be argued that this would help alleviate the problem of voter apathy, increasing turnout.

Of course, every system has its failings and STV (as well as other proportional representation systems) has been criticised for several reasons. The first of these is that it can lead to very large constituencies, particularly in areas like the Highlands where the population is not very dense. It is also true that the process of counting votes takes longer and that the voting system and ballot papers are much more complex. The first use of STV for elections to the Northern Ireland assembly saw a higher than normal number of spoilt ballots, however this year the number of spoilt ballots was only marginally higher (0.04%) than in the 2005 General Election. It is hoped that the introduction of electronic vote counting in Scotland, will speed up the process and lead to earlier results. The lack of "safe seats" in a STV system demands greater focus on campaigning which can cause a degree of exclusion of small, less well funded, parties.

Irish politicians have twice tried to change from the STV system. However the proposals were defeated in the referendum on both occasions perhaps implying that the Irish people are happy with this system despite its complexities. It will be interesting to see the reaction of the Scottish public on Thursday.