The Morrison government is pushing ahead with a crackdown on unions through new measures to make deregistering unions and disqualifying officials easier.
Legislation has been introduced to the House of Representatives on Thursday, with Industrial Relations Minister Christian Porter returning the Ensuring Integrity Bill to parliament.
Mr Porter says unions and employer associations hold a privileged position in the industrial relations system.
"Sadly we have seen some organisations and their officers continuously abuse these privileges, engage in repeated unlawful behaviour and fail to act in the best interests of their members," he told parliament.
"Some officers and organisations have proven wholly incapable of addressing their unlawful behaviour. They have nothing but contempt for the law."
Union officials will be automatically disqualified from holding their positions if guilty of criminal offences which hold penalties of five years in prison or more.
They will also be subject to a "fit and proper person test", while the minister or anyone with a "significant interest" could apply to deregister a union.
A public interest test would be imposed on mergers, like that of the powerful left-wing construction and maritime unions.
Prime Minister Scott Morrison put industrial relations on the agenda after his shock election victory, vowing to revive the bill the government says aims to stamp out union lawlessness.
Crossbench senators killed the legislation in the last term of parliament but the coalition is dealing with a smaller group of independents and minor parties in the new make-up.
The government will need four of six crossbenchers to get the bill through when it reaches the upper house.
Former Liberal Cory Bernardi and One Nation's two senators are expected to back the changes, but Centre Alliance's two votes will likely depend on extending the measures to corporations.
Tasmanian senator Jacqui Lambie could hold the crucial vote if the government insists on passing the bill without amendments.
Australian Council of Trade Unions president Michele O'Neil described the legislation as dangerous and extreme, saying it was important people were free from government and employer interference.
"All Australian workers benefit from the work of unions. If unions are shut down or silenced, who will stand up to the powerful, make sure workers get their rights and fight to improve workers' rights?" she told AAP.
"The Morrison government has overseen raids on journalists and is now attacking working people's freedom to run their own unions. These are dangerous attacks on fundamental pillars of democracy."
Mr Porter also introduced legislation to crack down on fraud related to worker entitlement funds, to ensure the funds work in the members' best interests.
The proposals give effect to a recommendation of the royal commission into trade unions.
The coalition is aiming to capitalise on controversy surrounding Victorian construction union secretary John Setka, with the ACTU calling for him to quit and Labor trying to expel him from the party.
The firebrand union boss was convicted of domestic violence offences including harassing his wife and breaching a court order, but is refusing to budge.
