A tribal conflict between two Pasifika descendants over the Indigenous sovereignty of the Chatham Islands is set to be decided by the New Zealand/Aotearoa Court of Appeal.

The mandated governance entity which manages the Treaty of Waitangi settlement has accused the government of reneging on a promise to remain neutral on the issues of tino rangatiratanga (self-determination and autonomy) of the Chatham Islands.

The Moriori Imi Settlement Trust is seeking a declaration of whether it would be unlawful for the Crown to enter into an arrangement with a Māori claim of the 10 islands belonging to the Ngāti Mutunga o Wharekauri iwi tribe, that would recognise and/or transfers interests which conflicts with the rival Moriori's own rights.

Descendants of both the Moriori and Ngāti Mutunga from and living on the Chatham Islands attended the Court of Appeal proceedings in Wellington last week before judges reserved a decision on the case.

The Moirori are a Polynesian group arriving on the Chatham Islands — traditionally known as Rēkohu — more than 500 years ago. They are also the people iwi tribes originally descend from in Aotearoa.

However in 1835, members of the Taranaki Ngāti Mutunga and other closely-aligned Ngāti Tame Māori from the Te Ika-a-Māui (North Island) sailed more than 800 kilometres eastwards to invade the islands they would call Wharekauri, going on to kill around 300 Moriori while enslaving more than 1500 of the tribe's survivors.

Hundreds of remaining Moriori inhabitants were only released from slavery following New Zealand's annexation of Chatham Islands in 1842, after a local proclamation from a magistrate 21 years later.

The heart of the case relates to the Crown signing an agreement in principle to settle the iwi's historical treaty claims from November 2022.

Acknowledging it had failed to consult the tribes back in 1842, the Crown's agrement includes a financial redress of up to $18 million, an additional option to culturally transfer significant lands to the iwi as a part of a cultural redress, as well as a shared redress with the Moriori.

It also outlines a broad settlement framework, including the recognition of Crown breaches of Te Tiriti (the Treaty of Waitangi), and the acknowledgement of Ngāti Mutunga o Wharekauri mana (authority) and tino rangatiratanga.

Moriori chief negotiator, Maui Solomon, said the settlement trust asked the Crown to remove the wording of tino rangatiratanga, however that request has so far been refused.

"During our negotiations with the Crown we started in 2016, we signed our settlement in 2020, the Crown undertook to us that they would remain neutral - as between the Moriori and Ngāti Mutunga - on issues of mana whenua and tino rangatiratanga - they have not done that," he told Radio New Zealand.

Mr Solomon said although the Te Tiriti was signed and applied in New Zealand to the Māori, the Crown claimed sovereignty over the Chatham Islands which ensured the Moriori should have the same rights under the treaty.

"Wherever they're claiming rights, they also assume the obligations," he said.

"We don't oppose Ngāti Mutunga having a settlement, per se.

"Even though we say, well, actually the Crown already rewarded Ngāti Mutunga by giving them all our land in 1870 by applying mainland custom of take raupatu (to alternate tribal hosts)."

The Moriori had preferred to settle out of court, Mr Solomon added.

However, Ngāti Mutunga o Wharekauri Iwi Trust chair, Monique Croon, pointed out it was disappointing to be in court over an issue they believed is straightforward.

"With tino rangatiratanga and our grievances, they are with the Crown, not against Moriori," she said.

"And so, we've always supported Moriori to have a settlement and again, we like to engage and we like to be part of sharing, working through that shared redress."

The Moriori's historic 2020 treaty claims did not include reference to mana whenua or tino rangatiratanga for them.

But Ms Croon stood by claims that the Moriori made a choice during negotiations with the Crown.

"Within their legislation in their deed have agreed to have shared redress with Ngāti Mutanga," she said

"At this stage, we still haven't been able to get together, engage with the Moriori on that shared redress...we all share whakapapa (a genealogical lineage).

"We live on a little island of Wharekauri where we're a small population - and it's important that we continue working together."

The Moriori Imi Settlement Trust chair Tom Lanauze disputes Ngāti Mutunga claimed tino rangatiratanga from the Moriori when they invaded the islands in 1835.

Even when Moriori people were slaughtered and enslaved there were still Moriori people on the Chatham Islands, Mr Lanauze added.

"We didn't lose our tino rangatiratanga by any means, in my view - and it's still there today," he said.

The Moriori Imi Settlement Trust applied for interim orders in the High Court in June 2025 that the Crown not take any further action in progressing the Ngāti Mutunga Treaty claim to the extent it would recognise that Ngāti Mutunga holds tino rangatiratanga over the islands.

Justice La Hood dismissed the application, finding that "interim relief isn't reasonably necessary to preserve Moriori's rights".

In December last year, Ngāti Mutunga o Wharekauri and the Crown initialled a draft deed of the settlement.