KEY POINTS:
The Privy Council has exposed the David Bain case as a lengthy, New Zealand-style Kafkaesque nightmare - a nightmare from which our highest judges will be trying to escape.
It's a tenet of our British-based justice system that the accused are entitled to a fair trial, that all
relevant evidence pertinent to a defendant's innocence or guilt will be put in front of a jury.
But in too many of our high-profile cases - think of the David Doherty affair - doubts remain over whether the police are unduly hasty at the evidentiary stage due to their drive to get criminal convictions.
We will never know whether it was David Bain or his father, Robin Bain, who slew five members of the troubled Bain family in their ramshackle Dunedin house early one morning in 1994.
But over the past 48 hours most of us would have heard a lot more about Robin Bain: his depressive nature, allegations he had committed incest with his daughter, and, his estrangement from his family.
Enough to at least raise questions as to whether he might have been the one to pull the trigger - not his son David.
David Bain's murder convictions are now quashed and The Crown Solicitor should order a fresh trial against Bain despite the lengthy time that has elapsed since that the first hearing.
The police will (again) suffer a blow to their credibility over the way the evidence was mustered against Bain, and their failure to investigate deeply or widely enough so that other evidence that might have cast doubt on their case, or pointed to Robin Bain's involvement, at least found its way to the defence team so they could present it to the jury.
What we do know - courtesy of the London law lords - is that it is New Zealand's highest judges, on whom we rely to correct miscarriages of justice, who have failed to do justice as far as David Bain is concerned.
The Privy Council believes the fresh evidence that emerged since Bain's incarceration provided a sufficient counter-point to that used to justify his initial convictions to warrant a fresh trial.
In their merciless dissection of an earlier ruling by our own Court of Appeal, the five British law lords: Lord Bingham of Cornhill, Lord Rodger of Earlsferry, Baroness Hale of Richmond, Lord Brown of Eaton-under-Heywood and Sir Paul Kennedy - leave no doubt that they consider Justices Noel Anderson, Andrew Tipping and Susan Glazebrook contributed to the "substantial miscarriage of justice".
The nine points of "fresh evidence" which the law lords considered pointed to the miscarriage of justice were also considered by the three Court of Appeal judges.
The say that in totality the points were of sufficient merit to warrant being put in front of a jury.
The law lords absolve the initial trial judge from any responsibility for this fiasco.
But they do point out it is the duty of the criminal appellate courts to seek to identify and rectify convictions that may be unjust. This can occur when a defendant is convicted and further post-trial evidence raises a reasonable doubt as to whether he would or should have been convicted had that evidence been before the jury.
Instead of ordering a new trial, as the law lords have now done, the trio of appellate judges took it upon themselves to establish David Bain's guilt "all but conclusively".
The law lords repeatedly make the point it is only a properly directed and informed jury that can determine the issue of guilt.
The issue is not whether there is or was evidence on which a jury might reasonably convict but whether there is or was evidence on which it might reasonably decline to do so.
And that a fair trial requires the jury to hear evidence it ought to hear before returning its verdict, and not act on misleading or false evidence.
"Even a guilty defendant is entitled to such a trial."
The law lords' criticism is sparse but powerful: "The board feels bound to rule that the court assumed a decision-making role well outside its function as a reviewing body concerned to assess the impact which the fresh evidence might reasonably have made on the mind of a trial jury."
The impact of that statement is immense.
What the law lords are saying is that the Court of Appeal judges - two of whom now sit on New Zealand's highest court, the Supreme Court, have failed in the performance of their most basic duty.
But Attorney-General Michael Cullen has refused to comment on the Privy Council's judgment. It will be up the Solicitor-General to decide, says Cullen, whether to order a retrial.
Unfortunately for the Attorney-General it is not that simple.
The Privy Council's judgment raises big questions about the competence of our appellate judges, and the ability for all New Zealanders to obtain justice in a situation where our rights to appeal to the Privy council have been abolished by the Government in favour of a home-grown Supreme Court.