Australia has a Westminster style of government, like Canada and the United Kingdom. In this system, a Prime Minister is the Head of Government while someone else is the Head of State. In Australia’s case, the Head of State is the Governor General, acting on behalf of the Queen. The Prime Minister must always have the confidence of the House of Representatives to stay in power.

Australia is a federation, like Canada. This means that there are several levels of government, including federal, state and territorial. Like many federations, Australia has two Houses: the House of Representatives (or Lower House) and the Senate (Upper House). The House of Representatives has 150 members whereas the Senate includes 76 members: 12 per state, plus 2 each for the Northern Territory and the Australian Capital Territory. Unlike Canada, Senators are all elected and they have the same power as Members of Parliament regarding legislation.

Like the United Kingdom, Australia originally had a first past the post electoral system. However, an electoral system called the alternative voting was introduced in 1918. This change came about because the Conservative Party and the Country party were splitting the right-wing vote. They were afraid that this situation would divide the right-wing vote and would let the left-wing Labor party win the next election. To remedy this situation, the Conservative government implemented the alternative vote system. This electoral system made it possible for right-wing voters to express their preferences for either the Conservatives or the Country party, while not allowing the Labor party to benefit from a split in the right-wing vote.

Alternative voting is used in elections to the Lower House in Australia. Voters rank the candidates in their constituency according to their preferences. First choice votes are counted first. If a candidate gets a majority of the votes, he/she wins. If not, the weakest candidate is eliminated and his/her votes are reallocated to the second preference of the voters who voted for that candidate. This goes on until one candidate receives a majority.

Voting is compulsory in Australia. The combination of alternative and compulsory voting leads to some interesting voting behaviour. Since alternative voting is a little more complex than your average voting procedure, it results in more spoiled ballots. Around 5% of the ballots are spoiled in Australian elections, mostly because voters write the same number twice or because they skip a number while writing down their preferences. Compulsory voting also leads to what is called “informal voting”, or casting a blank vote. Another observed behaviour is called donkey voting. This happens when voters who are forced to vote don’t have any preference when they get to the polls. They end up writing down the numbers from top to bottom. At some point in time, the candidates were placed in alphabetical order on the ballot, which resulted in an overrepresentation of candidates called Abbot or Aaron. Nowadays, however, the order of the candidates is determined randomly.