With the new Senate taking its place on 1 July, it is now possible for the next election to be held as a double dissolution where the House and the whole Senate are dissolved together.
A double dissolution is a significant constitutional event, not just an excuse for an early election. The power to dissolve both houses of the Australian Parliament is unique to the Australian Governor-General and is one of the few powers of the Governor-General that does not derive from the traditional powers of the monarch.
The House of Representatives was designed with representation based on the population of each state, but the Senate was to have equal representation for each state as well as fixed but staggered terms.
The Senate's design meant the popular will of the larger states as represented in the House could be blocked by the smaller states in the Senate. This was the price extracted by the smaller states to agree to Federation.
The price of the larger states agreeing to a strong Senate with equal representation was the double dissolution, allowing an obstructionist Senate to be dissolved in conjunction with the House at the request of the Prime Minister, a double dissolution, with the necessary election to follow. If the election did not resolve the deadlock, provision was also made for a joint sitting as a second mechanism to overcome the Senate, the two houses sitting together to pass the blocked legislation into law.
Only six of Australia's 43 elections have been double dissolutions, and only the 1974 double dissolution produced a joint sitting. Despite the state-based origins of the Senate and the double dissolution provision, disputes between the two chambers have always involved party politics rather than state issues.
A double dissolution requires a trigger. Any legislation passed by the House that is defeated, unacceptably amended or fails to be passed by the Senate, and then after a delay of three months is again defeated, unacceptable amended or fails to be passed by the Senate, becomes a double dissolution trigger. A government is permitted to accumulate a number of triggers. At any time in the first two and a half years of a House term, any trigger can be used by the Prime Minister to advise the Governor General for a double dissolution.
I find it almost impossible to see the circumstances under which the Gillard government would call a double dissolution. To achieve a trigger for a double dissolution, the government would need to have negotiated legislation through the House with the support of the Independents, and then find the legislation opposed by the Coalition and the Greens in the Senate. This would have to happen twice three months apart to become a trigger.
Given the Gillard government's precarious House position and its need to negotiate the passage of all legislation, I find it hard to believe the government would devote the necessary months of effort to trying to pass legislation the Greens will oppose in the Senate. Given its current polling, the Labor Party would be conceding government and giving away Senate seats if it called a double dissolution. I can't see why the Gillard government would work at creating double dissolution triggers, let alone even considering asking the Governor General to call a double dissolution.
A double dissolution would be more likely if the Gillard government fell and Tony Abbott became Prime Minister. Whether this occurs as a baton change of the Prime Ministership in the current parliament, or by an early House election, the Senate would remain unchanged, pitting the new Abbott government against a hostile Senate where Labor and the Greens maintained a majority.
Whatever happens in the House or to the Prime Ministership, the Senators taking their places on 1 July 2011 will be there until 30 June 2017, and the Senators who took their seats on 1 July 2008 will be there until 30 June 2014. The only Senators that an early House election could change would be the four Territory Senators, whose terms are tied to the term of each House of Representatives.
The only possibility an Abbott government would have to change the Senate ahead of its normal fixed term would be by calling a double dissolution.
There are two options for a double dissolution, one for a Coalition government formed in the term of the current House, and a second for an Abbott government formed after an early House election.
If an Abbott government formed without an election, it could set in train legislation designed to create a double dissolution trigger. This would probably take a minimum six months to arrange, time to pass the legislation, present it to the Senate under normal timetable procedures, achieve the first Senate block, then wait three months to again go through the normal procedures to achieve the second block.
Under the provisions of the Constitution, the last possible date for a double dissolution in the current term is 27 March 2013, which probably means the Coalition would need to take government by around the middle of 2012 to give itself time to arrange a double dissolution trigger. The Coalition would find more flexibility for timing of a double dissolution by coming to office after a separate House election.
If the Coalition took office after a separate House election, the last allowed date for a double dissolution would be pushed back. For instance, a House election held next month would allow a double dissolution to be held in early 2014, at the normal time for a half Senate election.
As from 1 July 2011, whether the Gillard government continues in office or the Coalition take office with or without an election, nothing can be done to Senate terms without a double dissolution. Writs for a half-Senate election for those Senators elected in 2007 cannot be issued until 1 July 2013, and the election must be held between August 2013 and May 2014, with new Senators to take their place on 1 July 2014.
What all these dates point to is that if the Gillard government is defeated in the House in circumstances that force it to resign, then the Coalition would probably want to go to an election as soon as possible rather than try to govern for the balance of the current House term.
One other point to make is that if the Labor government makes it through to the end of its term in the second half of 2013 and the Coalition won that election, then the Coalition would probably find it impossible to hold a double dissolution until the first half of 2015.
A full term Gillard government would go to a normal House and Half Senate election between 3 August and 30 November 2013. New Senators elected at the election would begin their terms on 1 July 2014.
While it is not explicit in the Constitution, I believe it is implicit in the fixed terms of the Senate that a double dissolution trigger can only apply to legislation first blocked by a Senate in place after 1 July 2014. The Constitution states the Senators take their place on the 1 July after their election. Any double dissolution triggers attempted before new Senators take their seats would not allow the new Senators to vote on the legislation.
An attempt to create a double dissolution trigger before the new Senators took their seats would attempt to terminate the terms of 108 Senators rather than the 72 implied by the Constitution.
Adding all this together, a double dissolution in the current term of the House must be held by 27 March 2013, but it seems this is highly unlikely unless the Coalition can form government before the middle of 2012. If the current government fell before its term, it would be in the Coalition's interest to come to office after a separate House election, giving itself an electoral mandate with which to threaten the Senate, and also allowing a double dissolution to be put off until early 2014 at a time when a separate half-Senate election would already need to be held.
If the Gillard government last its three years until the second half of 2013, any new Coalition government would find itself struggling to do anything about a double dissolution election until 2015.
Of course, if current opinion polls continue through the ne next election in late 2013, then a massive landslide might give the Coalition a chance to break the current Labor-Green majority at a half-Senate election for Senators in place from 1 July 2014. There wouldn't be the need for a double dissolution if that was the case.
(You can read more information on future election dates at the following Commonwealth Parliamentary Library publication. http://www.aph.gov.au/library/pubs/BN/pol/Aust_elections.pdf)
Update: I hope the attendees at today's anti-carbon tax rally read this post. It might help explain why their chant of "double dissolution now" was complete nonsense.