The country's most powerful unionist says she has no problem with members breaking industrial laws, arguing the rule of law only needs to be upheld when the laws are justified.

Sally McManus, who became secretary of the Australian Council of Trade Unions on Tuesday following the resignation of Dave Oliver, was defending the militant Construction, Forestry, Mining and Energy Union for taking unprotected industrial action.

Ms McManus said there was "no way" the peak union body would distance itself from the CFMEU, which is facing 118 separate legal proceedings, many of them regarding illegal strikes.

"It might be [illegal] according to our current laws. And the current laws are wrong. It shouldn't be so hard for workers in our country to take industrial action," she told the ABC's 730 program on Wednesday.