The government has considered contingency plans should the CFMEU win a High Court case to overturn its forced administration.
In August, the construction arm of the embattled union was placed into administration following allegations of criminal conduct and organised crime links on job sites.
The Fair Work Ombudsman is conducting more than 40 investigations into the building and construction industry involving most CFMEU branches across Australia, as well as its officials and employers.
Alleged coercive behaviour by union officials forms a significant proportion of the information received by the ombudsman.
A High Court challenge has been launched against the laws underpinning the forced administration on four grounds, including them being unconstitutional and negating implied freedoms of political communication.
At a Senate estimates hearing on Wednesday, Workplace Relations Minister Murray Watt was asked about the government's plans for the challenge.
"The government has certainly given consideration to what might be done if the high court case was to be successful," Senator Watt said.
"We're confident of our position, and we did everything we could in designing this legislation to ensure that it would be upheld."
Opposition employment spokeswoman Michaelia Cash criticised the minister's refusal to explain the decision to force the embattled union into administration, citing public interest immunity and that the case was before the courts.
Senator Cash said there was "no reasonable basis" for how the question about government policy could influence or undermine the court's ruling and pointed to Senator Watt's previous comments on the reason in TV interviews.
"I would like your response to that because I see double standards, quite frankly," she said.
Senator Watt cited a decision by Senator Cash as workplace relations minister to refuse to answer questions about a police raid on a union in 2017 that was before the courts.
Some blue-collar unions are outraged at the construction branch being placed into administration, saying it dispenses with due process, with investigations already underway and no one being found guilty in court.
But the hearing was told the reform that allowed the government to place the division into administration was made so it could be positioned for control by democratically elected, law-abiding people.
"The proposed legislation is necessary to end ongoing dysfunction within the division and to ensure it is able to operate effectively in the interests of its members," Department of Employment and Workplace Relations chief counsel Sarah Godden said.
Senator Watt also said the government would consider strengthening whistleblower protections after Senator Cash claimed some in the industry will not come forward because they don't believe protections are adequate to shield them from reprisals.
"I'm not aware of any reprisals ... so I think that others should take some confidence from that - that there is a system where people can make complaints," the minister responded.
More than 20 union leaders are considering an alternative peak union body to the ACTU that will stand up against the forced administration.
The leaders will meet in December under the banner of the National Building Industry Group Unions, with a political campaign and funding for union-aligned electoral candidates also on the cards.
