Tony Abbott ... being sued for defamation.

Tony Abbott ... being sued for defamation. Photo: Luis Enrique Ascui

When a group of construction workers held a rally outside the Melbourne headquarters of the building industry watchdog on a winter's day in 2010, they were addressed by a union official, John Setka, who promised a war of attrition. His language was lurid and vengeful:

''We know who's winning this battle. We're winning this battle, not them rats … There's no other way of putting it, they are f------s … They are shit …

''We're proud, we're construction workers … you're not working in some warm office like them f------s up there. And they've got the balls to try and prosecute us … Those rats, dogs, whatever they are, just remember one thing, when this is all over, and they don't exist any more, they've got to work elsewhere and we'll remember them because we know every f---ing one of them. We will never forget them.''

Setka remains the assistant secretary of the Victorian branch of the Construction Forestry Mining and Engineering Union, which put a video up on its website, which is why his words were recorded for posterity and could reappear in court.

The union was in confrontation with the regulator, the Australian Building and Construction Commission, from the day it was set up by, yes, Tony Abbott, the then minister for industrial relations. The commission's task was to do what police had failed to do and stamp out a subculture of coercion and featherbedding within the construction industry.

The regulator's first successful target was John Setka, who is now front-and-centre again in the union's dispute with Grocon in Melbourne. As The Age reported on November 4, 2003: ''John Setka, 39, was found guilty in Melbourne Magistrates Court of issuing a threat against [a building company] manager, who was due to appear against him in an industrial relations case.''

The watchdog won that 2003 battle, but the CFMEU has won the war. Thanks to Julia Gillard. Setka was right when he spoke to his members about the time when ''they don't exist any more''. The commission does not exist any more.

The Prime Minister, acting at the behest of the CFMEU, the ACTU and the Greens, has gutted an organisation that had effectively tackled the unions. Some of its functions were folded into Fair Work Australia, but what remains is toothless.

Remember Setka's words: ''When they don't exist any more … we'll remember them because we know every f---ing one of them. We will never forget them.''

Now the CFMEU is seeking to put the man who set up the commission, Tony Abbott, in court: Setka is suing Abbott for defamation. The material makes for fascinating reading.

The tripwire for this contest was a remark Abbott made in February to the Master Builders Association of Victoria. Abbott made no reference to Setka in his speech. But during questions he was asked about the campaign to abolish the commission. He replied: ''So many of you have got to go onto sites every day. You've got to deal with the John Setcos [sic] of this world.''

Three months later, on May 15, the CFMEU's lawyers Slater & Gordon, the former employer of the Prime Minister, notified Abbott that defamation proceedings had begun. The letter said that Abbott's comment, and other remarks, were understood to mean that Setka was a ''thug''.

Getting Abbott into the witness box during an election year and grinding away at him in court might look like a good idea.

But it is also easy to see why this defamation action could be a windfall for Abbott. For a start, he does not have to appear in court. His lawyers, in addition to disputing the imputations, could unleash the products of due diligence, going through Setka's career, issue by issue, in open court.

That may or may not not suit the government. It may or may not want John Setka representing the unions in the court of public opinion.

It may not want to draw further attention to Julia Gillard's links to the hard arts of the unions, and to her great gift to the CFMEU, shutting down the building industry regulator.

As recently as Friday, the opposition spokesman on industrial relations, Senator Eric Abetz, was accusing the CFMEU of flouting the law: ''The CFMEU are defying a Victorian Supreme Court order and bullying workers in Melbourne and Brisbane … creating posters labelling certain workers as 'scabs' in clear defiance of the Fair Work Act.''

This is the bargain that Julia Gillard made for power, a bargain she began making when, as a lawyer at Slater & Gordon, she set up a slush fund for a union that has since become mired in controversy.

In the public interest, I hope Setka v Abbott finds its way to court. It would raise matters which cry out for public scrutiny.