It is mired in complexity and even a resignation by Haumaha, which does not appear to be imminent, would not cauterise it.
Underlying it is the public's confidence in the police and the public's confidence in the Government to deal with challenging issues.
It involves Ardern's confidence in Police Minister Stuart Nash, and Nash's confidence in the judgement of Police Commissioner Mike Bush, who sat on the panel.
It was meant to be a fast inquiry – no more than six weeks - to establish whether the interview panel including State Services Commissioner Peter Hughes and the cabinet should have known about Haumaha's expressions of support in 2004 for former colleagues who had been accused of raping Louise Nicholas.
It has now been more than six weeks since the comments came to light publicly.
There were signs of trouble at the outset when Winston Peters was dealing with it as Acting Prime Minister.
The delay was in finding a suitable reviewer who would have the confidence of the Police, Maori and feminists.
That in itself is a reflection of the identity politics that is more important in this Government configuration.
National would have quickly found a retired judge or QC, which is what Ardern did last night in getting respected QC Mary Scholtens to undertake the inquiry.
Scholtens was Counsel assisting the 2004 Commission of Inquiry into Police Conduct, and has conducted an inquiry for the last Labour Government into how the whistle-blowing laws have operated. Scholtens is not considered a political risk at all – she is the wife of former National minister John Luxton and has worked for Governments of both hues.
The Maori dimension in the Haumaha problem is large. It involves Labour's relationship with its Maori caucus and its relationship with iwi leaders.
The Haumaha issue was raised privately with the Government at last week's iwi leaders' forum at Turangawaewae with high-level representation to keep him in place.
A group of Maori leaders campaigning for Haumaha have essentially framed it as an issue of Maori leadership and aspiration.
If Haumaha has been tempted to resign to limit the fallout for himself or the Police, those backing him could see that as surrendering.
At present only 11 per cent of the Police are Maori. It has a goal of 25 per cent of each recruit wing being Maori in order to get to about 14 per cent by 2020. Having Haumaha as Deputy Commissioner was an affirmation of that priority for Maori.
Ardern did know much about Haumaha back in May. Nash recommended him from a field of two recommended by the selection panel.
Nash's cabinet paper recommending him accentuates his role in addressing the over-representation of Maori in criminal justice system which is right in line with the Government's key priorities for reducing offending and the prison population.
Haumaha was already very well-known to Nash as an Assistant Commissioner – evidenced by Nash's chummy reference to "Wally" when he posted a humorous weight lifting video on Facebook suggests.
Haumaha is also close to Mike Bush and that would have carried some weight with Nash.
Bush had been viewed with some suspicion in Labour. He was appointed under Judith Collins' tenure as Police Minister and had run-ins with Labour in Opposition including a stoush with Trevor Mallard at a select committee over Bush's decision to give the eulogy at Bruce Hutton's funeral – an officer found to have planted evidence in the Arthur Allan Thomas case.
But Nash formed a good working relationship with Bush – whose term expires at the start of 2020.
The inquiry could well test existing loyalties. And the spotlight could fall on Bush as much as Haumaha.
Nash has said publicly that Bush told him he did not know about Haumaha's statements dismissing the allegations against his friends of rape. But he certainly knew Louise Nicholas strongly objected to his promotion.
Scholtens will probe that. But she also has licence to probe whether Bush knew and should have told the selection panel (and ministers) about more recent complaints by Justice and Corrections officials about intimidating behaviour working on a joint project.
Crucial in Nash's recommending Haumaha was that he had the backing of Labour's Coalition partner New Zealand First.
It is unlikely that Nash knew how close Haumaha's connections are to members of New Zealand First, as revealed by Jared Savage.
Scholtens should be considering whether the extent of those connections also constituted "relevant information" that should have been disclosed by New Zealand First to Nash, Ardern and the rest of the cabinet.
Ardern's confidence in New Zealand First Minister Tracey Martin may have dimmed.
Martin's officials let her down when they failed to do the necessary checks on potential conflicts of interest on the first reviewer, Pauline Kingi, who resigned after revelations by Savage.
Martin left herself down by suggesting that Kingi's endorsement of Haumaha was of no consequence.
It has been a mess. It is a small stain on Winston Peters' six weeks as Acting PM that he did not get it under control.
Ardern is back in charge.
