Retrospective laws introduced in NSW to help the state's corruption body fend off legal challenges are set to come under a High Court microscope.
NSW Premier Mike Baird says he is confident his new ICAC shield laws will stand up to High Court scrutiny.
Mr Baird introduced the retrospective laws, which affirmed all previous findings from the corruption watchdog, in an urgent bid to head off legal action from individuals seeking to have corruption findings overturned.
He was spurred to action after the High Court in April found the ICAC had overstepped its jurisdiction when it launched an inquiry into allegations made against state prosecutor Margaret Cunneen SC.
Now the lifeline legislation itself risks being struck down, after Justice Stephen Gageler gave the go-ahead to a bid from mining mogul Travers Duncan to challenge the validity of the Baird government's amendment in the nation's highest court.
Mr Duncan's lawyers have argued that the amendment was unconstitutional because it amounted to an instruction to the courts from the NSW government to ignore the ICAC's jurisdictional overreach, rather than an expansion of the ICAC's powers.
Mr Baird said he was confident his laws would stand up to the High Court challenge.
"We've taken legal advice in what we are doing, and in simple terms, I make no apologies for a zero tolerance approach to corruption," he said.
"All we have done is confirmed previous findings. We absolutely stand by that."
A High Court decision is likely to be several months off, with Mr Duncan's legal team due to file written submissions next month.