A BLANKET Commonwealth moratorium on coal seam gas would go against existing Commonwealth-State agreements - making it "almost impossible", according to an Australian National University environmental law expert.
Associate Director of the ANU Centre for Climate Law and Policy, Mr Andrew Macintosh, said while a moratorium was simple in legal theory, it was unrealistic.
Mr Macintosh said it would contravene agreements made in 1992 and 1997 by the Council of Australian Governments (COAG) in regard to State and Commonwealth roles in environmental protection.
The COAG agreements, while not legally binding, limit the intervention power of the Commonwealth to matters of national environmental significance.
"They've got the power, but it would go beyond the scope of what they've agreed to do," Mr Macintosh said.
"It would be stepping well and truly beyond the bounds of what the agreed framework for Commonwealth regulation is... and obviously the politics of it would be contentious to say the least."
Dr Tim Stephens from Sydney University, a constitutional law expert, agreed.
"Constitutionally it's difficult for the Commonwealth to have any sort of general moratorium on coal seam gas in a particular state or across the country," Professor Stephens said.
Dr Stephens said changing the Environmental Protection and Biodiversity Conservation Act was one way the Commonwealth could constrain the industry, but again, any areas restricted to CSG would have to boast significant national environmental value.
"It has to be something of national environmental significance for the Commonwealth to become involved... CSG exploration (for example) in Ramsar-listed wetlands or World Heritage areas, or impacts on threatened species."
Federal Member for Page Janelle Saffin recently called for the Commonwealth powers to be extended to include potential impacts on water resources, but Dr Stephens said that was unlikely.
"The Commonwealth has no power over water resources - that's why they have encountered issues managing the Murray-Darling," Dr Stephens said.
"I can't see that it's feasible unless the States were to give a referral to the Commonwealth - but of course they're not going to do that, because they want to promote things like CSG in their own jurisdiction."