So, Maori didn't cede sovereignty in 1840
The Waitangi Tribunal has found that "in February 1840 the rangatira who signed te Tiriti did not cede sovereignty. Rather, they consented to the Crown having power to control Pākehā, while recognising that, in situations where the Māori and Pākehā populations intermingled, questions of relative authority would have to be negotiated case by case."
This is not news. Even in my own text Society and Politics in 2004, I wrote: "The historical evidence suggests that Maori chiefs did not intend to cede sovereignty in 1840. Furthermore, they could not possibly have consented to the policies that were subsequently implemented by settler governments."
The Minister for Treaty Settlements and some iwi spokespeople are already drawing heroic conclusions about what the Tribunal's finding means today and for the future, even though those conclusions relate only to 1840. The Minister says the Queen still reigns; some iwi leaders are talking about separate nations.
Those who argue that the Tribunal's finding implies that iwi are effectively independent nations need to take account that "since 1985, when Maori approach the government for compensation for its unjust actions of the past, they are implicitly recognising the Crown’s present legitimate sovereign powers to govern, to make policies and to distribute public resources – otherwise they wouldn’t even be talking."
If you uphold the Tribunal's authority and findings, you need to recall that the Tribunal was created and empowered by Acts of the New Zealand Parliament (in 1975 and 1985), under the sovereignty of the Queen. You can't have your cake and eat it too. If you recognize the authority of the Waitangi Tribunal, you recognize the sovereignty of the Crown.