Maori Party co-leader Tariana Turia defended the right of Maori in the future to try to change the new foreshore and seabed legislation that is to get its first reading in Parliament today.

"I don't think we can ever say when legislation is being put in place that it is the end of any matter," she said. "Any legislation can be changed at any point in time."

There were bound to be Maori in the future who would say the new law was not fair or just but that was for the future to decide.

The Marine and Coastal Area (Takutai Moana) Bill fulfils the Maori Party promise to repeal Labour's Foreshore and Seabed Act 2004.

It asserted Crown ownership and extinguished the right of Maori to claim customary title in the courts.

The repeal bill will be supported by Labour at least to the Maori Affairs select committee.

But Labour's David Parker yesterday suggested that National should have obtained an undertaking from the Maori Party leadership that the repeal bill was the "full and final settlement of the legal framework for the foreshore and seabed rights".

Attorney-General Chris Finlayson said he had not sought such an acknowledgement "nor can I reasonably be expected to".

It was not for him, "a humble worker in the vineyard", to go around demanding written acknowledgements from other political parties.

The reading of the bill was delayed for the return of the Maori Party co-leaders, Mrs Turia and Dr Pita Sharples, from overseas.

The bill restores the right of Maori to claim customary title in the High Court, a new form of property title.

Successful litigants will become the legal owners of the relevant area and will have most rights of private ownership, including the right to commercially develop it within the constraints of laws such as the Resource Management Act.

But it cannot be sold and public access must be guaranteed.

Maori Party MP Hone Harawira told his colleagues on Monday he would not be supporting the bill.

He is expected to outline his reasons later today but his opposition in the past has been on the basis that he wanted all of the foreshore and seabed vested in Maori title.

Mrs Turia said she had had a guarantee from Mr Harawira that he would not be leaving the party over the bill.

Prime Minister John Key said the fact that Mr Harawira was not voting for the repeal legislation meant National probably got it about right.

"I want legislation which is enduring and which the majority of New Zealanders can support. I think we got that about right. The fact that Hone's not going to vote for it probably just confirms that."