Australia 'has one of the highest levels of spoiled or informal ballots among established democracies'. Levels of informal voting at the last two elections are consistent with informality levels in the 1984 and 1987 elections.
The AEC's 1987 analysis of informal voting showed that 48% of informal ballots were informal because of 'defective numbering', 25% because of 'ticks or crosses', 16% because they were blank, and 10% because of scribbles or writing without a valid indication of preferences.
The treatment of 'Langer-style' votes changed in 1998. Langer-style ballots are typically numbered so that, at a point chosen by the elector, the preferences stop or begin to repeat (for example, 1, 2, 3, 3, 3 …). Before 1998, such ballots were counted up to the point that the numbering stopped or became non-consecutive, and were then classified as exhausted. Until 1993, the number of Langer-style votes was small, but in 1996 there was a considerable increase. It is possible this was due to the well-publicised court action against Albert Langer. Since legislative change in 1998, Langer-style votes have been counted as informal, and their number has declined considerably.
In 2004, as shown in Table 1, informality increased at a national level to 5.18%, from 4.8% in the previous election.
|Informal voting in House of Representatives elections (%)|
|New South Wales||6.1||5.4||4.0||3.6||3.1||3.1||4.6||5.7||2.2|
|Australian Capital Territory||3.4||3.5||2.9||2.8||3.4||3.0||3.5||4.7||2.2|
More on the history and background of formal voting requirements and informality can be found in the AEC's Electoral Backgrounder Number 18, Informal Voting.