Monday's Supreme Court decision will reshape expectations on central Government, local Government and the Waitangi Tribunal on their approach to dealing with iwi interests, Chapman Tripp says.

The decision allows Ngati Whatua Orakei to continue to argue their legal rights as mana whenua in the Tamaki isthmus and continues to establish the place of tikanga in the common law of New Zealand, Chapman Tripp's Hoa Rangapu Whakarae (chief executive partner) Nick Wells said.

"There are three key outcomes of this decision – first, the setting of the precedent that Crown conduct in negotiating Treaty settlements is judicially reviewable. Secondly, this case paves the way for it be easier to challenge ministers' decisions. Thirdly, the rights of iwi should be considered when central or local Government deal with them. This third outcome becomes more interesting as the place of tikanga in the law continues to develop."

Wells, along with Chapman Tripp partner and the firm's national head of litigation Justin Graham and senior associate Laura Fraser, has acted for Ngati Whatua Orakei since the start of the proceedings (from the High Court upwards).

On Monday, the majority of the Supreme Court allowed, in part, Ngati Whatua Orakei's appeal for a judicial review of the Crown's conduct in negotiating the Marutuahu Collective's Treaty settlement – previously struck out by both the High Court and the Court of Appeal.

"However, Chief Justice Sian Elias went further, and allowed Ngati Whatua Orakei's appeal in its entirety, permitting Ngati Whatua Orakei to continue their judicial review claim in the High Court to test their legal rights as mana whenua in the Tamaki isthmus," Wells said.

This victory follows Ngati Whatua Orakei's Treaty settlement with the Crown, concluded by legislation in 2012, which recognised widespread Crown alienation of Ngati Whatua Orakei's land in the Tamaki isthmus.

"Ngati Whatua Orakei's gifting of 3,000 acres of land in central Auckland in 1840 (including Auckland CBD, Parnell and Orakei) to forge a relationship with the Crown is considered the first alienation of many, and by 1855, Ngati Whatua Orakei was basically landless – carrying with it devastating social, economic and spiritual implications."

The Crown is currently negotiating further Treaty settlements with other iwi in the Tamaki isthmus and applying the "overlapping claims policy" –meaning when multiple iwi lay claim to a particular area, the Crown encourages them to resolve it amongst themselves.

"Many iwi consider this as a pragmatic approach, rather than one based on historical accuracy or tikanga."

Wells said the now-permitted High Court proceedings will also include a head-on challenge of the overlapping claims policy with many iwi and hapu calling for reform.

"It remains to be seen how the Crown will respond to this judgment but the threat of judicial review by iwi will certainly be a concern and could tilt the scales towards reform," he said.

The information in this article is for informative purposes only and should not be relied on as legal advice. Please contact Chapman Tripp for advice tailored to your situation.