168 - Just Vote 1: The rise of preferential voting

In Australia today, we have two main methods of election when a single representative is being chosen.

Both methods require the voter to number their preferences, with a one for their most preferred candidate.

Under both methods, a vote can be passed on to lower preferences if their most preferred candidate is knocked out, but the difference is about whether voters need to number those other boxes or not.

Under compulsory preferential voting, or CPV, the most common method used for the House of Representatives and single-member elections in most states, the voter must number every box.

There might be a few exceptions to deal with mistakes, but generally voters must clearly express a preference between every candidate.

If they don't do so, their vote is considered informal and is not counted.

Under optional preferential voting, or OPV, most prominently used to elect the New South Wales Legislative Assembly, voters don't have to number any other boxes.

If they don't clearly indicate their preferred candidate, then the vote can't be counted.

But as long as there is a single clear one, their vote counts.

If all of their preferred candidates are excluded, the vote exhausts, so not every formal vote will remain in the count until the end.

These two methods have existed for at least a century, and during that time there has been a constant tension over the method of voting.

Early in the 20th century, those parties that tended to lose out from the flowing of preferences advocated for a return to first past the post, but this option was discredited by the 1970s.

Since then, the argument has focused on the exact method of marking preferences.

Do we force every voter to mark preferences for every candidate, which ensures stronger flows of preferences and a winner with a majority of the vote, but at the cost of more informal votes and denying a voter the choice to simply not mark a preference? Or do we keep informal voting low and give voters the freedom to not mark preferences, even if it means candidates are elected with less than half the vote and preferences don't flow as strongly? Where a political party lands on this question often depends less on their political principles and more on what might help them.

If your party does better on preferences from other candidates or needs preferences to coordinate between multiple parties, you'll likely support whatever method ensures preferences flow as strongly as possible.

Compulsory preferential, that is.

But if your party is relatively united and doesn't gain much preferences, you'll likely support the method that minimizes the flow of preferences, first past the post or optional preferential voting.

For most of the 20th century, it was the parties of the right who benefited from preferences, while Labor usually experienced preferences as something that would flow against them and lose them elections.

This dichotomy then flowed into party positions on the electoral system.

Preferential voting was generally introduced by conservative governments, while Labor governments advocated for first past the post or optional preferential voting.

This split lasted as late as the 1980s.

The Whitlam government attempted to introduce optional preferential voting for federal elections in the 1970s, and the Hawke government supported OPV in 1983.

But in more recent years, the positions have flipped.

Preferences have favored parties of the left, with Greens' preferences being crucial for Labor election victories, while the Coalition has been more unified.

This led to the Queensland Labor government switching the state to CPV in 2016.