The Supreme Court has ruled the government must honour a land deal struck in 1830s between the New Zealand Company and Māori in the Nelson region.
The decision in favour of Wakatū descendants has come after a seven-year court battle with the Crown.
Wakatū Incorporation, representing about 4000 shareholders descended from the original Māori customary landowners, argued in court that a promise that Māori would retain one tenth of land purchased by the New Zealand Company was never upheld. The trust was also meant to exclude the iwi's pā, urupā and cultivations from the land purchases.
Four of the five Supreme Court judges found the Crown owed fiduciary duties to the trust, which was to reserve the land for the benefit of the Māori customary owners.
The Supreme Court ruling overturns previous High Court and the Court of Appeal decisions.
Chief Justice Sian Elias said there was "overwhelming evidence on the historical record that the Crown intended to and did deal with the reserve land as a trustee".
The Supreme Court sent the case back to the High Court to determine a remedy.
The Tenths deal
The New Zealand Company bought 151,000 acres to settle the Nelson region, of which, under the deal, 15,000 acres (6110ha) were to be held in a trust for Māori landowners in perpetuity.
The trust was called the Nelson Tenths Reserve.
With the signing of the Treaty of Waitangi in 1840 came a law which allowed only the Crown to purchase land from Māori. Commissioners were required to look at pre-1840 purchases.
It was confirmed that the land purchases were valid and a tenth of the land was to be reserved for Māori.
Ten thousand acres were never transfered into the trust. Of the 5000 that were, more was lost, and by 1977, when the Nelson Tenths Reserves were vested in the Wakatū Incorporation, just 1626 acres (658ha) remained.
Wakatū argued in the court that in 1840 the Crown agreed to act as trustee.
It said Māori landowners were never granted their full entitlement of land and pā, urupā and kai plots, which should have been excluded from the agreement.
The incorporation argued the Crown had breached its legal duties by significantly reducing the already allocated land and failing to allocate a further 10,000 acres.