The Government took the Waitangi Tribunal to court on Monday over its unprecedented move to subpoena the Children's Minister before she repeals a section of the Oranga Tamariki Act.
It's the first time a minister has been required to give evidence - or face a criminal offence.
Across the road from the Beehive, two arms of government are in a constitutional clash.
"This is an unorthodox - to use the words of the complainants before the tribunal - and actually an unprecedented event," Solicitor-General Una Jagose KC said in court.
"Up until 11 days ago we had a nice workable state of constitutional balance of mutual respect and constraint. That state of equilibrium has been shattered by the conduct of this minister," said Matthew Smith for Ngāti Pikiao.
It's Parliament versus the Waitangi Tribunal over the latter's decision to summons the Children's Minister because she refused to voluntarily appear or respond to questions. Instead she lawyered up.
"The basis of the challenge is the coercive aspect of the summons which obviously has the corollary of being an offence to not meet it," Jagose said.
The tribunal's hearing an urgent claim about the coalition's plan to repeal what's known as Section 7aa of the Oranga Tamariki Act.
That clause requires a consideration of tamariki's whakapapa and mana when deciding where to place them.
"My worry is that without that commitment in law that it's really up to the leadership in the organisation," Dr Hope Tupara, president of the Māori Women's Welfare League, told Newshub.
ACT campaigned on repealing it - and got it inked in its coalition deal, because of concerns it was leading to reverse uplifts where Māori tamariki were being removed from Pākehā.
"Very simply we want to prioritise the health of a child, of our most vulnerable children," said Prime Minister Christopher Luxon.
The Crown says it was a promise the coalition was built on and a decision made by Cabinet.
"The tribunal mistakenly thinks the minister is the moving mind, they say. They're mistaken by that," Jagose said in court.
But the Cabinet papers show officials don't support the repeal and it was argued that's why the minister needed to explain her thinking.
"That's what the tribunal is grappling with - how can you have a policy that the minister is putting out to Cabinet in her final Cabinet paper that is so disconnected from the policy analysis of the officials undertaken in the free and frank sense," lawyer Matthew Smith said.
Also at play is the notion of comity - that's the mutual respect and restraint between two arms of government - the courts and Parliament. Each side argued the other trampled on it.
"Comity is a two-way thing so it requires mutual respect and also candour," lawyer Matanuku Mahuika said.
Justice Andru Isac will make his decision on Wednesday.
