Law professor and prominent Trans-Pacific Partnership (TPP) critic Jane Kelsey says the Government's claim the trade deal is a "damned sight better" than it was a few weeks ago is just spin.

She reserved her strongest criticism for Acting Prime Minister Kelvin Davis, saying he was just plain wrong to say multinational companies would not be able to sue the Government in international courts over policy changes that hurt their profits.

In an eventful weekend in Vietnam, TPP talks between world leaders lurched between consensus and chaos, with Prime Minister Jacinda Ardern eventually saying while not a perfect agreement", the latest text of the TPP was "a damn sight better than what we had when we started".

But Prof Kelsey, who teaches at the University of Auckland, says she went through the available information and concluded little has changed.

"It's hard to see how it's gone to being an agreement that Labour, the Greens and NZ First said they couldn't support the ratification of, to being the best thing since sliced bread," she told The AM Show on Monday.

"There is virtually nothing that I can find that is a significant concession."

Labour has previously highlighted five major concerns with the TPP - foreign ownership of housing, Treaty concerns, tariffs, Pharmac security and investor-state dispute settlement (ISDS) clauses. ISDS clauses allow companies to take Governments to court over policy changes that could hurt their bottom lines - courts which operate outside the New Zealand justice system.

Both Ms Ardern and Mr Davis say "80 percent" of the ISDS concerns have been allayed.

"Anyone who takes up a contract with a Government is no longer able to sue through ISDS," Ms Ardern said on Sunday.

"If an overseas company wanted to sue the New Zealand Government for breach of contract, they'll have to go through our New Zealand domestic courts instead of through an international tribunal," Mr Davis added on Monday.

"It's basically the same as any New Zealand company would have to go through if they wanted to sue the Government for breach of contract."

"Kelvin Davis is wrong," says Prof Kelsey, saying Mr Davis either hasn't read or doesn't understand the TPP.

"The problem is you have politicians who don't understand this stuff, and that's one of the big frustrations of those who have been raising [concerns]…

"One of the difficulties is we get politicians that come out with soundbites about what's new and what's better, and I don't know whether they're not well-briefed or they're just taking shortcuts, but certainly the spin that we've heard from [Trade Minister] David Parker and from the Prime Minister don't match up to what's still in the text. Basically it's the same deal, they've suspended a few things."

And those suspensions could be lifted if the US rejoins TPP, she warns.

Support qualified, even amongst business leaders

Michael Barnett, chief executive of the Auckland Chamber of Commerce, says critics like Prof Kelsey play an important role in ensuring free trade agreements live up to the lofty promises politicians make of them.

While he "absolutely" supports the TPP, he has concerns it'll only benefit "big boys" like Fonterra.

"I'm looking at the thousands of small businesses in New Zealand and saying, what I'd like to see is an agreement that benefits them."

Ms Kelsey also questions whether any trade generated by the TPP will benefit average Kiwis.

"Do we really want to sell more frozen beef carcasses to Japan to employ 60,000 workers who are actually low-paid workers, many of them migrant workers?"

Newshub.