Graeme Samuel, who penned the now five-year-old review of the federal environment protections, says the national interest exemption is too open to interpretation and at risk of legal disputes and exploitation by ministers.
"Also, the risk to the minister is there'll be a conga line of lobbyists that will be outside their door saying, 'Well, look, you just use the national interest exemption'," the former consumer watchdog chief warned at a parliamentary hearing in Canberra.
The national interest override has been included in the Environment Minister Murray Watt's overhaul of the Environment Protection and Biodiversity Conservation Act.
The federal government is on its third attempt to overhaul the laws designed to protect nationally significant species and habitat from destructive development.
Senator Watt maintains he has delivered a package that will both restore nature and streamline approvals for renewables, housing and other valued development.
The necessary support from either the Greens or the opposition has not yet been secured.
Prof Samuel recommended a national interest override in his 2020 review but he said he should have been more careful of his definition of the national interest and circumstances it should be used.
"That didn't work out," he told the Senate inquiry.
Instead, he now believes national interest should be weighed up as one of the matters taken into account in determining if development approval should be granted.
"In other words the 'national interest' should become a consideration to be balanced against other considerations, in particular the protection and restoration of the environment," he wrote in his submission to the inquiry.
Senator Watt has stressed national interest powers as drafted would be used "rarely" in matters relating to security and emergencies.
Green groups appearing before the committee said any national interest exemption should be confined to a narrow set of circumstances that did not include fossil fuel projects.
"The idea that massive fossil fuel polluting projects can possibly be in the interests of a nation that is already suffering from extreme climate harm ... is beyond absurd, Greenpeace Australia Pacific chief executive David Ritter told parliamentarians.
