It seems safe to assume that the evidence the Crown presented against the so-called "Urewera Four" was the best they had. And it is a source of more than mere embarrassment that it failed to secure a conviction on the most serious charge they had brought.
Police had presumably done their share of private blushing before the trial began. Less than a month after the raids, in Te Urewera and elsewhere, that introduced the word "terrorism" into domestic political discourse, the Solicitor General, to his obvious consternation, declined to prosecute under the Terrorism Suppression Act the 17 arrested in the raids.
His reasons were plain: that the evidence was insufficient and the legislation was "complex and incoherent" and "almost impossible to apply to domestic circumstances". But he also stressed that the police had uncovered some "very disturbing activities". What they were, we were not allowed to know.
Then the Crown dropped firearms charges against 13 of the 17 defendants after the Supreme Court ruled covert video evidence inadmissible (a matter finally tidied up by the passage into law this week of the Search and Surveillance Act 2012), though allowed its use against the four who finally went to trial because of the seriousness of what police were alleging.
So what had started as 17 alleged terrorists became four people guilty of firearms offences; the jury failed to reach a verdict on the charge of belonging to an organised criminal group.
The way in which the case has been pared away bit by bit in the 4 years since it began would be comical if its implications were not so sobering. The police's dogged persistence was at times reminiscent of Monty Python's Black Knight, who demanded to fight on even as his limbs were removed one by one and only when he was reduced to a limbless torso conceded that "we'll call it a draw".
This is far from a draw. It is a comprehensive rout for the police, made the more humiliating because it is largely self-inflicted. The case failed because, as Tame Iti's lawyer Russell Fairbrother remarked, it was based on speculation and not hard fact. It required the jurors to draw too many inferences to fill in gaps in the evidence. To their credit, they declined to do so.
It goes without saying that Tuesday's verdicts should be the end of the matter. The trial, the most expensive in our criminal legal history, has already cost the taxpayer north of $2.5 million and it would be throwing good money after bad to pursue a retrial where the evidence is unlikely to be better.
Private costs have been incurred as well. Marama Mayrick, one of the original 17, faces legal bills of $35,000 because she has too good a job to qualify for legal aid. She will not be alone in having been seriously penalised, both financially and in terms of reputation. Meanwhile, the damage to the relationship between the police and the public - Maori in particular - is incalculable.
This is not to say that those caught up in this mess are free of blame. Whatever was going on in Te Urewera was plainly pretty dodgy: at the very least, the people caught on camera were being spectacularly stupid and it's a thin line that separates recklessness and tragedy.
But the prosecution failed to prove that the more objectionable utterances of the accused were genuinely criminal as opposed to the braggadocio of blowhards and Tame Iti's remark that police were "looking through a keyhole" at what was going on rings true.
On the other hand, it strains credibility that the object of the exercises was training people for security work in Iraq; if the participants had such noble aims there would have been no need for such secrecy.
Still, the police raids, which needlessly terrified women, children and the elderly, were a massive movie-style over-reaction. It is quite possible that this was always a job for a community cop, who might have banged some heads together and given a few people 24 hours to sort themselves out.
Nothing presented in court plainly urges against that conclusion. And now that it's all over, the police need to account for their conduct of this whole sorry affair. It's time to front up, not fade away.