New laws that validate past findings of the New South Wales Independent Commission Against Corruption (ICAC) have come into effect after a swift passage through Parliament overnight.

The corruption watchdog was potentially facing a flood of lawsuits from people it had previously investigated, after a successful High Court challenge to its jurisdiction.

But there was bi-partisan support for a bill introduced into Parliament yesterday morning to validate all the ICAC's past findings.

The legislation also protects the corruption watchdog's actions to date in current inquiries, including the Australian Water Holdings and Liberal political donations scandals.

The bill was passed in the Lower and Upper houses late last night and has been signed into law.

Former ICAC assistant commissioner Anthony Whealy QC has welcomed the new law.

Mr Whealy said he applauded both sides of government for moving so quickly.

He said that, while he had not seen the legislation yet, he was sure there would be multiple challenges.

"Very wealthy people in the community who don't like the findings that have been made against them will have the best lawyers in Australia working flat out to see if there's someway that they can poke a loophole in this new law," he said.

"They'll be doing their very best to try and avoid the consequences of this new law.

"So I think we'll just have to wait and see."

ICAC future powers under review

The ICAC's powers were subject to a successful High Court challenge brought by NSW crown prosecutor Margaret Cunneen.

Ms Cunneen was accused of advising her son's girlfriend Sophia Tilley to fake chest pains to avoid a breath test after a car accident in May last year.

The High Court found the commission did not have the power to investigate Ms Cunneen because the allegations did not constitute corrupt conduct under the ICAC Act.

The ICAC said the High Court decision narrowed its powers significantly and undermined some previous corruption findings, including those made against Travers Duncan and three other businessman relating to dealings with former Labor minister Eddie Obeid over a mining lease.

The New South Wales Government has asked former High Court chief justice Murray Gleeson to lead a review of the watchdog's future jurisdiction and powers.

The review will consider the appropriate scope for the ICAC's jurisdiction, any legal measures required to provide ICAC with the power to expose serious corruption and whether those powers should be limited or enhanced.

A report is expected by July 10.