Certainly there is one trigger for a double dissolution but note this prediction: that trigger is not going to be the legislation to re-establish the Australian Building and Construction Commission. It will pass the Senate next month with amendments to satisfy almost every crossbench senator. My advice to those Canberrans contemplating a summer holiday in the northern hemisphere is: take it. There will be no federal election in Australia this southern winter.

The 2016 election will be for the House of Representatives and half the Senate and it will take place in September, October or November.

Malcolm Turnbull has made his strategy clear.

His first priority has been to rig the Senate electoral system in favour of the big parties, meaning the Liberals, Nationals, Labor, Greens and Nick Xenophon. That Labor (eventually) chose principle over the temptation of the bait was not enough to thwart Turnbull. The other four took the bait and voted for the rig which gave Turnbull his recent victory in the Parliament.

His second priority comes into play when the above objective is achieved. He believes he has achieved the degree of rigging needed for him to risk a double-dissolution election. The media (Malcolm Mackerras dissenting) agrees with Turnbull.

So why do I dissent?

My essential argument is contained in an article published in The Canberra Times on December 9 last year. The article was titled in print as "Party list unconstitutional". It argued that it would be a violation of the constitution to turn the present single transferable vote system into a party list system for Senate elections.

Late in the morning of Monday, February 22, an announcement was made on the government's position on Senate reform.

A quick parliamentary inquiry was held on Tuesday, March 1, at which I denounced the legislation. Meanwhile, the federal Joint Standing Committee on Electoral Matters received 107 submissions of which mine was No. 106.

On the morning of that same Tuesday there appeared in The Canberra Times an article by me titled "Senate voting changes contemptuous of constitution".

The Commonwealth Electoral Amendment Bill passed through both houses of Parliament on the afternoon of Friday, March 18.

Over the following weekend I succeeded in persuading my friend Senator Bob Day (Family First, South Australia) that there was a 50-50 chance of success were he to launch his challenge to what is now the Commonwealth Electoral Amendment Act 2016.

The announcement of his launch came on Wednesday, March 23.

All my commentary has been one condemnation after another of what I now call "the legislated Senate electoral system". Turnbull says it is the law of the land. Not yet it isn't! I think it is probable the High Court will strike it down.

Working through a well-known Sydney senior counsel I have made and sworn my seven-page affidavit on which I have worked virtually full-time over the past month.

Throughout this entire decade-long debate the Proportional Representation Society of Australia and I have been the only people in the country who have put principle first. Our principles are the democratic values of the Australian constitution.

Section 7 commands: "The Senate shall be composed of senators for each state, directly chosen by the people of the state, voting as one electorate."

Section 24 commands: "The House of Representatives shall be composed of members directly chosen by the people of the Commonwealth ..."

Those are our principles – "directly chosen by the people" being the rule for all our federal politicians, except for senators filling casual vacancies.

Our constitution's principles tell us that all our federal politicians must be elected in a CANDIDATE-BASED electoral system.

There is one difference between the PRSA and me. I have thrown myself into this High Court challenge while they have stood on the sidelines.

However, if the court makes the right decision I know that the overwhelming majority of PRSA members will join me in giving three loud cheers to a great Australian democrat, Senator Bob Day.

Malcolm Mackerras is a visiting fellow at the Australian Catholic University's Canberra campus. malcolm.mackerras@acu.edu.au