ELEANOR HALL: To less welcome news for the Government now, and yet another headache for the Commonwealth over its $10-billion plan for the Murray-Darling Basin.

The Federal Water Minister, Malcolm Turnbull, won't reveal details of his negotiations with the Victorian Premier.

Steve Bracks has also revealed little about what he's managed to secure from the Commonwealth on its contentious Murray-Darling Basin plan.

But one legal expert is warning today that if Victorian farmers are granted special conditions, the deal could well be unconstitutional.

Jane Cowan has our report.

JANE COWAN: Through a spokesman, the Federal Water Minister, Malcolm Turnbull, says there's been no sweetheart deal with Victoria.

But he's declined to reveal exactly what's he's agreed in order to bring that State back to the negotiating table, when just weeks ago the Victorian Premier declared the deal "dead in the water".

Labor's Water Spokesman, Anthony Albanese, is no more enlightened than anyone else, and he says that's part of the problem.

ANTHONY ALBANESE: Well, what's clear is that what is required is everyone to work in the national interest, and that's why there needs to be transparency in the process and the Government will need to state exactly what has been agreed with the different parties to any arrangements that are made.

We'd call upon the Howard Government to detail any arrangements that have been entered into, and indeed to lift the cloak of secrecy.

JANE COWAN: With irrigators in Queensland and New South Wales nervous about whether the Victorians might have secured special conditions, the water ministers in those States are anxious to see the detail of what's been agreed behind closed doors.

The Queensland Water Minister, Craig Wallace, this morning told Parliament he's waiting for official confirmation of what any deal struck by Victoria would mean for irrigators in other States.

CRAIG WALLACE: Although Queensland remains strongly committed to the national plan for water security, we'll still need to review the final details of the Commonwealth's proposal, including changes negotiated by Victoria.

If Victoria and the Commonwealth find common ground, Queensland also should benefit from any deal that is struck.

Some Queensland irrigators have said that they are worried about Victoria and the Commonwealth doing a side deal, but the Beattie Government will be working to ensure there is a level playing field.

JANE COWAN: There are two drastically different possibilities here. Victoria's tactics could have won that State special conditions, or it could have won those conditions for all the Murray-Darling Basin States.

If that's the case, it's something the Minister Malcolm Turnbull wasn't prepared to spell out for The World Today, leaving people like the Director of the Centre for Comparative Water Policies and Laws at the University of South Australia, Jennifer McKay, to speculate. She says it would be difficult for the one piece of legislation to sustain different conditions between the States.

JENNIFER MCKAY: Well, this is the interesting legal point, but not many people have seen the proposed legislation, so we can't answer that, but most referred powers the legislation becomes uniform throughout the whole country, and this is done to achieve a social purpose and in fact to unify the laws.

So, yes, the worry would be that there's going to be some type of special arrangement in these referred powers that the other States are forced to refer all their allocation powers, and Victoria maybe is only, refers allocation powers in this region, a lesser amount of them, and still retain some control, which would of course … the other States would feel aggrieved about that.

JANE COWAN: Jennifer McKay says if the legislation did enshrine any differences between the States, that would undermine the whole point of having a national water plan.

JENNIFER MCKAY: You do this in order to achieve uniformity. You don't do it to, if you want differences you persist with the existing situation, which where the state has the power and there are enormous differences.

So it would be an unusual and a very interesting legal precedent to do that in a federation, and it would be forging new legal grounds and it may well be unconstitutional, because other sections of the constitution prohibit discrimination between states or parts of states and trade rules, and there's a number of other parts of Section 5139 that would be relevant to any interpretation or legality of this law.

JANE COWAN: So do you think it's more likely that any concessions Victoria's managed to achieve will apply to every State?

JENNIFER MCKAY: I would, I think that is probably more likely, and therefore everyone would benefit by their behaviour in holding out and seeking further clarification.

So I think the options are open to create something with differences between the States or something that is uniform, and I think the, one with differences between the States would be harder to legally justify.

ELEANOR HALL: And that's the University of South Australia's Jennifer McKay, ending that report by Jane Cowan