The Speaker presides over the House of Assembly, which is composed of forty-seven Members, each representing a separate electorate. The House of Assembly electorates are fixed by the Electoral Districts Boundaries Commission to ensure equal representation for all South Australians.
The term of a Member is for the life of the Parliament (four years). Casual vacancies are filled at a by-election in the electorate where the vacancy has occurred. Any person qualified to vote in House of Assembly elections is entitled to nominate for a seat. Members of the House of Assembly are elected by secret ballot using the preferential system of voting and counting. To be elected, a candidate must receive an absolute majority of votes, that is, more than 50 percent of the number of formal votes cast.
If no candidate receives an absolute majority of first preference votes, the second preferences of the candidate who received the fewest first preference votes are examined and distributed to the remaining candidates. The distribution of the next available preferences from the candidate with the fewest votes is repeated until a candidate is elected with an absolute majority.