In recent weeks, since it’s been assured that we are heading towards a double dissolution election, political conversations have moved onto preferences, the order of senators on the balance paper and a lowered bar for election. But why are we talking about these things — what makes this election different to any since 1987?

What is a double dissolution election? 

In a standard election, all 150 lower house MPs are up for re-election at the end of their three-year terms, but only half of the 76 senators, who are elected on alternating six-year terms, have to fight for their seats. In a double dissolution election, all 76 Senate places are up for grabs — and that changes the game in quite a few ways.

A double dissolution election can only be declared if the Senate has blocked a piece of legislation twice — that’s called a “double dissolution trigger”. While this Parliament has had more than one trigger, the one that set this in motion was the bill to re-instate the Australian Building and Construction Commission. We’ve been heading for this election since the Senate refused to pass the bill at a special sitting in April.

How often do they happen? 

Double dissolutions aren’t standard fare in Australia, with only six so far in our history. We’ve had double dissolution elections in 1914, 1951, 1974, 1975, 1983 and 1987. The most famous is the double dissolution called by governor-general John Kerr after he sacked Gough Whitlam’s government.

Do they actually make it easier to pass bills? 

In 1914 and 1983, the government lost the double dissolution election, so the new governments did not pass the legislation that had been blocked (1975 is, of course, a special case, since the election was not called by the government).

In 1983, Malcolm Fraser called an early double dissolution election in an attempt to catch the Labor opposition off guard and force it to go to the election with Bill Hayden as leader. Instead Bob Hawke led the party to the election and into government.

In 1951, Robert Menzies’ government wanted to reverse the proposal to nationalise the banks, which had been put in place by Ben Chifley’s government. Following the double dissolution election, Menzies’ government was successful in this.

In 1987, Bob Hawke led the country to a double dissolution election over the Australia Card Bill, but the election did not deliver a majority in the Senate, and the bill was eventually abandoned.

Will it be easier for minor parties and independents to get elected? 

Despite the recent changes to how senators are elected, designed to make it easier for voters to control where their preferences go, a double dissolution election means the quota required for election is lower.

Unlike in the lower house, senators aren’t required to get more than 50% of the vote. To determine the quota, we start with 100% of the votes and divide that by one more than the number of senators to be elected. In a standard election, when six senators are elected in each state, that quota is 14.29% (100/7 is 14.29%).

In a double dissolution election, however, the quota is just 7.69%, meaning the hurdle for the number of votes is lower. This could work in favour of minor parties — at the 2013 election Motoring Enthusiast Senator Ricky Muir started with less than 1% of the vote, but preferences got him to 14.29%. This time, preferences don’t need to go as far, but changes to above-the-line voting — electors can now number boxes one to six, instead of just one and letting the party direct preferences — will also come into play.

If all senators are elected together, which ones will recontest in another three years? 

Half the senators elected on July 2 will only be elected for three years, so that in following elections we can return to electing half the Senate at a time on six-year terms. Only 72 of the 76 senators are subject to this — the four senators representing the ACT and Northern Territory face re-election every election.

This is the section of the Electoral Act that declares how it is decided which senators are unlucky enough to get three-year terms:

electoral act

Clear as mud, right?

According to Crikey‘s own Poll Bludger, William Bowe, this means that the AEC should conduct a recount of the vote as if only the 12 elected were taking part in a normal half-Senate election, which would end with six “winners”, who reached 14.29% quota, and six “losers”, who did not.

“The winners should, in theory, get the longer term, and the losers the shorter term. However, the act just says the AEC has to conduct the count. It doesn’t say that anything actually needs to be done about it — and the constitution actually leaves it to the Senate the determine the matter in whatever way it chooses,” Bowe said.

Leaving it the Senate to decide means that this does not always happen in practice, Bowe says.

“The last time we had a DD in 1987, Labor and the Australian Democrats, who between them had a majority in the Senate, decided they didn’t like the result of the recount. So they instead voted to give the longer terms to the first six candidates elected in the original count, and the shorter terms to the last six. That just happened to mean Labor and the Democrats got more long-term seats, and the Coalition more short-term seats. This was done despite the fact that the latter method produces distorted results under the Senate’s [proportional representation-single transferable] vote electoral system (it was fine before [proportional representation] was introduced in 1949), which is precisely why the Hawke government legislated the recount method in 1984.”

The allowance in the constitution means that the new senators could get to decide who gets a six-year term and who gets three years, so we will have to wait and see.