An innocent cafe meeting between CFMEU leaders and Boral executives was distorted by lawyers in a "conspiracy" designed to criminalise union activity, the union's Victorian boss says.
Prosecutors dropped blackmail charges against CFMEU state head John Setka and his deputy Shaun Reardon on Wednesday, ending a long legal saga.
The allegations related to a meeting with Boral executives Paul Dalton and Peter Head at a coffee shop in April 2013.
It was alleged Setka and Reardon threatened to blockade Boral plants and trucks if the concrete company refused to meet union demands.
But the charges were dropped in the middle of a committal hearing in Melbourne Magistrates Court.
"After a careful assessment of the evidence, I have instructions to withdraw the charges," prosecutor Ray Gibson said.
Setka and Reardon were charged in 2015 after a joint Victorian and federal police unit investigation, following a referral by the trade union royal commission.
Outside court, Setka said the case was an attempt by the coalition government and others to criminalise union activity.
"It's definitely a witch-hunt," he told reporters.
"You've got all sorts of organisations that were involved in this conspiracy.
"It was to criminalise trade unionism in this county. That's all it was about."
He said there was evidence of talks involving Boral, former prime minister Tony Abbott and former Victorian premier Denis Napthine.
"It was just a conspiracy, all the way through," he said.
The meeting at North Melbourne's Auction Rooms cafe was called by Boral in the hope the union would lift a black ban on its cement deliveries.
At the time, Boral was the subject of a boycott linked to the union's industrial fight with building giant Grocon.
The CFMEU wanted to appoint its own health and safety representatives at Grocon sites because of safety concerns, following deaths.
Defence lawyer Peter Gordon said Setka and Reardon were innocent victims of the distortion and destruction of evidence.
"One coffee shop conversation about work safety at Grocon got distorted, and it got fabricated into a blackmail threat," Mr Gordon said outside court.
"Neither of Boral's men took the coffee shop conversation as any kind of threat."
The union pair fought to get the charges dropped, even taking the case to the Supreme Court.
"It's a fantastic result for workers all across this country," Setka said.
"They're trying to take away workers' rights. We're there to fight for workers' rights."
During the committal, questions were raised about the Boral executives destroying their original notes about the meeting.
It was also revealed key witnesses redrafted their statements time after time, one doing as many as 41 drafts.
The Victorian Trades Hall Council labelled the entire process a "a politically motivated farce from start to finish", designed to smear the Australian union movement.
"Malcolm Turnbull should be the first person to apologise," secretary Luke Hilakari said.
But Federal Jobs Minister Michaelia Cash stood by the royal commission and denied the decision was embarrassing to the government.
"The CFMEU are without (doubt) one of the most notorious, in fact, they are the most notorious union in Australia," she said.
Setka and Reardon will not seek to have legal costs paid by the state.