The peak trade union body is rejecting Turnbull government legislation to stamp out secret payments between employers and unions.
Under legislation introduced by Prime Minister Malcolm Turnbull last month payments with the intent to corrupt will carry a penalty of up to 10 years in prison and $900,000 in fines.
In its submission to a Senate inquiry into the proposed changes, the ACTU says the bill should not be passed.
Ahead of its appearance before a hearing in Canberra on Wednesday, it argues there was no stakeholder consultation and the new liability offences are unprecedented.
The council calls for proper consultation and says the proposed offences should not just be confined to interactions with trade unions.
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"There is no reason to target union related bribery," the ACTU says.
"If the aim is to deal with corruption including bribery then the law should be amended to deal with that issue generally."
Under the changes payments for legitimate purposes would still be allowed, but would also have to be fully disclosed.
The ACTU says it does not object to the basic principle of disclosing benefits in the course of bargaining, but has some concerns about the drafted provisions.
The Employment Department, which will also appear on Wednesday, cites the findings of the Heydon royal commission into trade union governance in its submission.
"The royal commission found that the payment and receipt of corrupting benefits was widespread, and that such arrangements have no place in a lawful and democratic society," it said.
The Council of Small Business Australia will also give evidence on Wednesday.
