Elections and Representation: WACE Year 12 Politics and Law
“Analyse the electoral systems used in Australia and how they shape representation and the formation of government”
Australia uses full preferential voting to elect the House of Representatives and a proportional (single transferable vote) system for the Senate. These different systems shape who wins seats, how governments are formed, and how minor parties gain a voice.
What this dot point is asking
SCSA wants you to understand that the way votes are counted is not neutral: the choice of electoral system directly affects which candidates and parties win representation, and therefore who forms government and exercises political power. You need to be able to describe the systems, compare their effects, and evaluate how democratic they are against principles such as one vote, one value.
The House of Representatives: full preferential voting
The House of Representatives is elected from 151 single-member electorates (divisions), each returning one member. Australia uses full preferential voting, also called instant-runoff or the alternative vote. Voters must number every candidate in order of preference (1, 2, 3 and so on) for the ballot to be formal.
To win, a candidate needs an absolute majority, meaning more than 50 percent of the formal vote. If no candidate has a majority on first preferences, the candidate with the fewest votes is eliminated and their ballots are distributed to the next preference marked. This continues until one candidate passes 50 percent.
This system tends to produce stable single-party (or coalition) majority government, because it favours larger parties and rewards the broadly acceptable candidate. It also allows voters to support a minor party first without wasting their vote, since preferences flow on.
Australia does not use first-past-the-post (where the candidate with the most votes wins even without a majority). Full preferential voting guarantees the winner has the support, by preference, of an absolute majority of voters in the seat. This is a common comparison point in exam answers.
The Senate: proportional representation
The Senate uses a proportional system based on the single transferable vote (STV). Each state elects 12 senators and each territory elects 2. At a normal half-Senate election, 6 senators are elected per state.
Candidates must reach a quota to be elected. For a half-Senate election the quota is calculated by the formula: total formal votes divided by (number of vacancies plus one), then add one. Surplus votes above the quota are transferred at a reduced (fractional) transfer value, and candidates with the fewest votes are excluded and their preferences distributed, until all vacancies are filled.
Because seats are shared roughly in proportion to vote share, the Senate is far more likely to elect minor party and independent senators (the Greens, One Nation, and others). This frequently denies the governing party a Senate majority, so the Senate acts as a house of review and a check on the executive.
Since 2016, Senate voting allows voters to vote above the line (numbering at least six parties in order) or below the line (numbering at least twelve individual candidates), which ended the old group voting ticket system that produced "preference harvesting".
How votes become government
Government is not formed by winning the most votes nationally; it is formed by the party or coalition that commands a majority on the floor of the House of Representatives (at least 76 of 151 seats). The party leader who can command that confidence is commissioned as Prime Minister by the Governor-General.
This means a party can win government with less than half the national two-party-preferred vote if its support is efficiently distributed across seats, and a hung parliament results when no party reaches 76 seats, forcing negotiation with crossbenchers (as in 2010).
Representation and electoral fairness
Australia promotes equality of representation through several features: compulsory enrolment and compulsory voting (enforced by the Australian Electoral Commission), independent redistribution of electoral boundaries to keep enrolments roughly equal, and the principle of one vote, one value within the House. The Senate, by contrast, deliberately gives every state equal representation regardless of population, so a Tasmanian vote carries far more weight than a New South Wales vote. This tension between equal representation of people and equal representation of states is central to evaluating how representative the system is.
A common task asks you to show how the Senate quota produces proportional outcomes. Work through it in steps.
Step 1: State the quota formula
For a half-Senate election with 6 vacancies, the quota is the total formal votes divided by (vacancies plus one), then add one. With 6 vacancies that is votes divided by 7, plus one, which is about 14.3 percent of the vote.
Step 2: Apply it to vote shares
A party on roughly 14 percent of the state vote reaches a quota and wins a seat. This is far lower than the absolute majority needed in a single-member House seat, so smaller parties can win.
Step 3: Distribute surpluses and exclusions
Votes above a quota transfer to later preferences at a reduced (fractional) value, and the lowest candidates are excluded with their preferences distributed, until all 6 seats are filled.
Step 4: Draw the conclusion
Because a modest vote share secures a quota, the Senate regularly elects Greens, One Nation and independents, denying the government a majority and turning the Senate into a genuine house of review.
A frequent error is assuming the party with the highest national vote automatically governs. Government depends on holding a majority of seats in the House of Representatives, not on the raw national vote. Another common slip is confusing the two systems: the House uses preferential voting in single-member seats, while the Senate uses proportional STV in multi-member states. Do not mix them up.
Exam-style questions
Questions in the style of SCSA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
WACE 2022-style18 marksAnalyse how the electoral systems used for the House of Representatives and the Senate shape representation and the formation of government in Australia.Show worked answer →
An 18 mark response needs both systems described, their effects compared, and an evaluation against democratic principles.
House. Full preferential voting in 151 single-member electorates; a winner needs an absolute majority, with preferences distributed until a candidate passes 50 percent. Effect: favours major parties and tends to produce stable majority government.
Senate. Proportional representation by single transferable vote; candidates need a quota, surpluses transfer at a reduced value. Effect: elects minor parties and independents, so the government rarely controls the Senate, making it a house of review.
Formation of government. Government is formed by whoever commands a majority on the floor of the House (76 of 151 seats), not by the highest national vote; a hung parliament forces negotiation, as in 2010.
Evaluation. Weigh one vote one value (strong in the House) against the Senate's equal state representation, which over-weights small states. Markers reward accurate mechanics, comparison of effects, and a judgement on how representative the system is.
WACE 2020-style7 marksExplain how full preferential voting works in the House of Representatives and one strength and one weakness of the system.Show worked answer →
A 7 mark response needs the mechanics plus a balanced strength and weakness.
Mechanics. Voters number every candidate in order of preference. A candidate must reach an absolute majority (more than 50 percent). If none does on first preferences, the lowest candidate is eliminated and their ballots distributed to the next preference, repeating until someone passes 50 percent.
Strength. The winner has majority support by preference, and voters can rank a minor party first without wasting their vote.
Weakness. It favours larger parties and can under-represent minor parties relative to their first-preference share, and exhausted preferences can occur. Markers reward correct mechanics and one developed strength and weakness.