South Australian State Election, 2006 - Electoral System

Electoral System

South Australia is governed according to the principles of the Westminster system, a form of parliamentary government based on the model of the United Kingdom. Legislative power rests with the Parliament of South Australia, which consists of The Sovereign (represented by the Governor of South Australia), the House of Assembly (lower house) which forms government, and the Legislative Council (upper house) as a house of review. Forty-seven members of the lower house represent single-member electorates and are elected under the full-preference Instant-runoff voting (IRV) system for fixed four-year terms. The independent State Electoral Office, which conducts elections, is responsible for a mandatory redistricting of boundaries before each election to ensure one vote one value. At each election, voters choose half of the 22 upper house members, each of whom serve eight-year terms in a single statewide electorate.

The Legislative Council is elected under the preferential Single Transferable Vote (STV) system through a means of Group voting tickets. Voters can choose to vote for a ticket by placing the number '1' in one of the ticket boxes "above the line" or can vote for individual candidates by numbering all the boxes "below the line" (54 in the 2006 election). In above the line voting, ticket votes are distributed according to the party or group voting ticket registered before the election with the election management body. As more than 95% of ballot papers are above the line, this form of voting often leads to pre-election trading between parties on how each party will allocate later preferences to other parties and candidates.

Voting is compulsory once enrolled in South Australian elections, which results in turnout rates above 90 percent. Informal voting, which occurs when a voting slip is not valid, is at a rate of under five percent. Voting slips are informal when they are not filled out correctly, such examples are not numbering subsequent numbers, not filling out all the candidate boxes with numbers (except the last candidate), or in some other way that is verified by the State Electoral Office as illegible. South Australian elections have some features that are unique to the rest of Australia.

As elections have fixed four-year terms, the election date of 18 March 2006 was known well ahead of time. The Electoral Act stipulates that the election is to be held on the third Saturday in March every four years. The election campaign must run for a minimum of 25 days or a maximum of 55 days, therefore the Governor would have needed to issue writs for the election by 21 February 2006 at the latest. On 20 February, Premier Mike Rann invited Governor Marjorie Jackson-Nelson to issue writs for the election. In accordance with electoral regulations, the Electoral Commissioner then advertised key dates for the election of the House of Assembly and half of the Legislative Council – close of rolls on 27 February 2006 at noon, nominations to be received by 2 March 2006 at noon, polling day on 18 March 2006, and the return of writs on or before 28 April 2006.