Double dissolution speculation is getting the better of a number of online commentators lately. Antony Green explains this mechanism, unique to the Commonwealth constitution, and the political options available to the government.

The tedious topic of a double dissolution seems to be doing the rounds again. In particular, there seems to be quite a lot of badly informed commentary on political blog sites on how a double dissolution would be brought on.

Let me quote one website commentator who manages to encapsulate these misunderstandings in two sentences.

There will be a DD in early 2015 whether Abbott wants it or not (he very unlikely to want it as by then 2PP polling will be something like 60-40 against him!). Shorten will deny him supply, and rightly so.

This comment is wrong for two fundamental constitutional reasons. First, a Prime Minister may choose to call a double dissolution election but they cannot be forced to call one. Second, you cannot get a double dissolution from blocking a supply bill, though a government may choose to call a double dissolution on other grounds because supply is blocked.

So let me go through the mechanism of a double dissolution and also clear up this issue with supply bills.

The key point to make is that a double dissolution of the House and the whole Senate, followed by an election and possibly a joint sitting, is a significant constitutional event, not some euphemism for an early election.

It's Constitutional

The double dissolution mechanism is set out in section 57 of the Constitution. It was drafted and endlessly debated in the 1890s constitutional conventions. It was a constitutional mechanism that allowed a government with a majority in the House of Representatives to overcome the blocking power of the Senate.

The need for some method to resolve deadlocks between the House and Senate was created by the decision to give the Senate virtually co-equal powers with the House, something that was unworkable under the Westminster model of responsible government unless a deadlock provision was provided.

As it was envisaged, Section 57 was a mechanism that would allow the population of the larger states as represented by the majority government in the House of Representatives to overcome the blocking power of the smaller states in the Senate. While the Senate never became the state assembly imagined by the constitutional drafters, the double dissolution power was still an important mechanism and has been used six times.

The double dissolution power is unique to the Commonwealth constitution. It was a power created for the Governor-General to use in their name, not as the representative of the Queen. It is a power created by the Constitution and is not a reserve power inherited from the British Monarch.

Putting the double dissolution mechanism in dot points, it consists of the following steps -

A bill must first pass the house and then be rejected, fail to pass or be unacceptably amended by the Senate.

A bill must first pass the house and then be rejected, fail to pass or be unacceptably amended by the Senate. After a period of three months, the bill may be re-presented to the House. After its passage through the House, if it is again rejected, fails to pass or is unacceptably amended by the Senate, then the legislation has become a "trigger" for a double dissolution.

After a period of three months, the bill may be re-presented to the House. After its passage through the House, if it is again rejected, fails to pass or is unacceptably amended by the Senate, then the legislation has become a "trigger" for a double dissolution. The Prime Minister may choose to use one or more triggers as ground for a double dissolution of both chambers followed by an election for the House and the whole Senate. This is not allowed to take place in the last six months of the House's term.

The Prime Minister may choose to use one or more triggers as ground for a double dissolution of both chambers followed by an election for the House and the whole Senate. This is not allowed to take place in the last six months of the House's term. After the election the legislation must be presented to the new House, and after its passage, must be presented to the new Senate.

After the election the legislation must be presented to the new House, and after its passage, must be presented to the new Senate. If the Senate again rejects, fails to pass or unacceptably amends the legislation, then the Prime Minister can request that the Governor-General summon a joint sitting of the two chambers sitting and voting as one on the legislation. At the joint sitting, a simple majority of those members and senators present can pass the legislation which is then signed into law by the Governor-General. A legislative (as opposed to ceremonial) joint sitting cannot occur without a double dissolution election having first taken place, and no other legislation can be considered at a joint sitting.

The originally drafted Section 57 contained a requirement that three-fifths support was required for a bill to pass at a joint sitting. This was part of the draft constitution that failed to pass in NSW at the 1898 referendum. NSW Premier George Reid had the provisioned weakened to requiring a simple majority, one of several changes that strengthened the power of the Commonwealth government and the power of the larger states and led to the acceptance of the Constitution at a second referendum in 1899.

This mechanism can be used for normal legislation but is almost impossible to be used in relation to appropriation and supply bills.

The term "supply" has a specific meaning for the parliament, but in its common use means the main appropriation bills that sets out how much money has been set aside for the normal working of each department in the next 12 months.

The current appropriation bills were introduced with the budget speech last Tuesday. They specify how much money each government department can spend between July 1, 2014 and June 30, 2015. These bills are in the process of passing the House, will soon go to the Senate, and have to be passed by by both houses before June 30 this year or government will cease to function on July 1.

That is why the blockage of the appropriation bill cannot be a trigger for a double dissolution. As currently formulated, it is not possible for the appropriation bills to be defeated and the parliament come back and debate them again in three months time. The government would have run out of money by then.

Budgets usually include other pieces of legislation covering detail of the budget. For instance the current budget will require legislation or regulation changes that cover pensions, tax rates, Medicare and the like. Any legislation of this type could be used as a double dissolution trigger after a second blockage, though regulation disallowance couldn't. Oppositions tend to be selective in deciding which budget measures to oppose, the least popular measures being least likely to become double dissolution triggers.

Unless there is other legislation that the government can use as a trigger to obtain a double dissolution, the blockage of supply can only force a House of Representatives election. There is no ability for the blockage of appropriation bills as currently formulated to be used as a double dissolution trigger.

Hard for history to repeat

So what happened to produce double dissolutions in 1974 and 1975 following the blockage of budget bills?

The answer is that both of those double dissolutions had a background in the blockage of supply or appropriation bills, but in both cases it was triggers created by other blocked legislation that permitted double dissolutions to take place.

A key point of difference between today and the Whitlam government is the timing of the budget. Today the budget is in May and the appropriation bills cover the whole of the next financial year. Until the mid-1980s the budget was in August, and what is more correctly known as a "supply" bill was passed in May to authorize government expenditure between 1 July and 30 November, pending the passage of the budget.

In 1974 it was the blockage of the interim supply bill that saw Gough Whitlam advise for a double dissolution based on six other pieces of legislation. Whitlam warned the Senate he would do this if it blocked supply, and the holding of the election was made easier as the election replaced an already announced separate half-Senate election.

In 1975, the Opposition-controlled Senate deferred the passage of the budget bills, demanding the government first announce the holding of an election. The government had interim supply to get it through to 30 November, perhaps longer if it saved money on its spending.

In the end the Governor-General Sir John Kerr intervened to resolve the on-going deadlock before the supply period ran out. He appointed Opposition Leader Malcolm Fraser as Prime Minister, who promptly authorised his Senate members to pass the budget, and then requested a double dissolution based on other Whitlam government legislation. The subsequent Fraser government made no attempt to revive the legislation used as the basis for the double dissolution.

If the budget bills had not been passed by the Senate on November 11, 1975, then Kerr and Fraser would have been in a very messy constitutional pickle by being unable to fund the holding of an election. But that is a scenario for alternative histories rather than relevant to today.

For historical reasons I do not believe the Labor Party will even consider blocking the appropriation bills. The Labor Party has demonised conservative controlled upper houses that blocked supply against Labor governments in Tasmania in 1925 and 1947, the Cain Labor government in Victoria in 1947, and the Whitlam government in 1974 and 1975.

That using upper houses to block supply and bring on an election is a last-resort weapon can be shown by the reticence of Coalition-controlled legislative councils in the early 1990s to block supply and bring down the Lawrence Labor government in WA or Kirner Labor government in Victoria.

The only time the Labor Party has voted against supply in an upper house in a situation where it would bring down a government was in Victoria in 1952, and that was a much more complex case involving a government that also lacked a lower house majority.

But let me assume for a moment that the Labor Party would go against its history and vote with the Greens in the Senate to defeat the appropriation bills. What happens next?

First, if the government chose to call an election of any sort, an interim supply bill would have to be passed allowing government to continue functioning from July 1 until a new parliament could convene.

When the Hawke government announced its intention to call a double dissolution election for early July 1987, it had to continue with the sitting of parliament until supply had been passed to cover the period until after the election.

But what election could the government call? At this stage the only option is for a separate House election. There couldn't be a half-Senate election and there could not be a double dissolution because no trigger exists that would permit Section 57 to come into play.

Possible triggers

There are several pieces of legislation concerning the repeal of the Gillard's climate change legislation that could become triggers in the near future. (You can see a full list of possible future triggers via this link.)

Of these bills, the only one that has passed back through the House and been re-presented to the Senate is the Clean Energy Finance Corporation (Abolition) Bill 2013. If this were defeated in the next month, it would permit the calling of a double dissolution once interim supply was arranged.

But using this bill as a double dissolution trigger would be the Prime Minister's choice. If supply was blocked and the government was forced to an election, the Prime Minister could call a House election. Even if the Prime Minister had a double dissolution trigger, it is his choice to use it. The government can be forced to an election but it can't be forced to a double dissolution.

But two final political points also need to be kept in mind.

First, any attempt to hold a double dissolution under the Senate's current electoral system would be almost impossible. There would be even more parties and candidates contesting given the near halving of the quota for election. There will not be another election until changes are made to the Senate's electoral system. Those changes can be legislated quickly but will need time to be implemented before an election can be held.

A second political point is that the Abbott government's budget is not the sort of budget you introduce if you desire an early election. It is the classic tough first term budget introduced in the hope that in three years time the anger will have subsided and the economy and budget would be in a better position.

So everyone should just calm down and understand that in all likelihood the current government will be in place until the second half of 2016.

Even if the government gets multiple double dissolution triggers, it will not use those triggers unless it thinks it can win the subsequent election.

It is noteworthy that having floated the idea of a double dissolution last week, the government has quickly talked down the suggestion.

In my opinion there is not going to be a double dissolution in the near future, and even in the more distant future, I cannot see any possibility of a double dissolution before late 2015 or the first months of 2016. Even then, a double dissolution will not occur unless the government thinks it will win.

Antony Green is the ABC's election analyst. You can read his election blog here.