Jobs and innovation minister Michaelia Cash could face cross-examination in court over her office's involvement in tipping-off the media about police raids on union offices.
The Australian Workers Union's (AWU) legal representatives have informed the Federal Court that the union will seek to subpoena Cash, as well as her former media adviser David de Garis and former Fair Work Ombudsman (FWO) official Mark Lee.
The subpoena applications will be formally made in the next day and if successful, all three will be required to appear in court at the end of the month to give evidence and face cross-examination about their knowledge of the leaks and subsequent raids.
“We believe the raid and the investigation itself to be unlawful," AWU national secretary Daniel Walton told BuzzFeed News. "That is why the AWU has gone to the Federal Court.
“We think the testimony of [Cash, de Garis and Lee] is important to understanding exactly what happened.”
The AWU launched its Federal Court challenge following revelations from BuzzFeed News that Cash's office tipped off the media about the October 24 raids by the Australian Federal Police (AFP) on the union's Sydney and Melbourne offices.
The union aims to probe the validity of the raids, which were part of an investigation by the Turnbull government–established watchdog, the Registered Organisations Committee (ROC), into donations made by the union over a decade ago when it was led by current Labor leader Bill Shorten.
Walton claims the ROC investigation was politically motivated and invalid, and that the subsequent raids on their offices were unlawful.
He says AWU staff in Melbourne and Sydney were informed of the raids by members of the media, who arrived at the offices well in advance of police and began broadcasting live into news bulletins.
De Garis resigned from Cash's office last year after admitting he tipped-off journalists ahead of the raid. He hasn't spoken publicly, or revealed who told him the raids were about to occur. He's one of four staff members to leave Cash's office since the leaks were exposed.
At the time of the leaks Lee was on loan from the FWO to the ROC and knew ahead of time that the search warrants were being sought. He's since resigned from the FWO, blaming intense media scrutiny, and hired the lawyer responsible for Rebel Wilson's historic multi-million dollar defamation win to represent him. Lee has denied he was the source of the leak.
Cash claims the leak occurred without her knowledge but has continually refused to say whether any other ministers or staff members were involved.
Last month BuzzFeed News spoke to a journalist who claims they received a phone call from then justice minister Michael Keenan's office informing them of the raids before they took place.
Cash has refused to say whether she had had conversations with Keenan about the AWU raid, claiming public interest immunity in the wake of the AFP's investigation.
The AFP launched its investigation into the tip-off the day after the raids, concerned that a leak of this magnitude could have put officers' lives in danger and compromised its investigation.
AFP commissioner Andrew Colvin told Senate Estimates last month that he's not ruling out whether more people, including a police officer, were involved in the potential "unauthorised disclosure of government information" — a crime which carries a maximum penalty of two years in prison.
The AFP has conducted interviews with more than 10 staffers in ministerial offices, but not with ministers. The AFP has also spoken to people from the ROC and the Fair Work Commission. No charges have been laid and the investigation is ongoing.
The hearing is set for March 26.
CORRECTION
Mark Lee was informed by the ROC that warrants had been sought for the AFP raid. An earlier version of this post incorrectly stated he knew the warrants were being executed.