KEY POINTS:
Joe Karam has been a splendid nuisance. He has nagged and niggled and gnawed on every scrap of evidence left by the deaths of the Bain family in Dunedin, and would not let go. He would not let go after one appeal, and a second, and a third
upheld David Bain's conviction.
He would not let go when a petition to the Governor-General gave his case yet another hearing and again it was dismissed in the Court of Appeal. He sought leave to go to the Privy Council, possibly the last New Zealand case that will have that opportunity, and got it.
In London he has gained vindication. The Law Lords have looked at his fresh evidence and concluded "a substantial miscarriage of justice" has occurred.
They have not found David Bain innocent, though that is what he must be presumed if no retrial is held, but they have quashed the convictions for which he has served 12 years in prison.
If no retrial is possible after so long, or if a new trial acquits him, questions of compensation arise.
But not for Mr Karam. The former All Black and self-made businessman took on a personal crusade for someone he scarcely knew, with no prospects of financial gain. He could not have known the difficulties he would face or perhaps even his own capacity for perseverance in the face of so many setbacks. Once he was convinced Bain was framed, he could not let go.
To many he seemed obsessive. Like most convinced campaigners he could not understand why everybody was not persuaded that fragmentary inconsistencies in a Crown case were crucial, and that they found the alternative construction of the crime - that David's father killed the family, then himself - completely inexplicable.
At last he has found judges who agree with him, at least about the evidence he has unearthed. In his moment of vindication, he can be forgiven a few swipes at his doubters.
"We had to go 12,000 miles and get out of what is apparently a very self-serving small community in New Zealand to get a fair hearing," he said.
And: "In New Zealand it is very difficult to fight town hall."
And: "It is time for the people who have been fighting David Bain and me to reflect upon what they have been doing all these years, and the politics and personal interests that have driven the fight against David Bain."
If this case is indeed one of the last from New Zealand to be taken to the Privy Council, it will haunt our criminal justice system.
Those who wanted to keep the Privy Council as our court of final appeal always argued that it was healthy to have a reference to judges so removed from the domestic legal community.
Every time our highest court of criminal appeals declines to overturn a conviction now, disappointed parties might wonder what the Privy Council would have done.
But no court, however distant, is infallible. Justice will sometimes miss the truth everywhere. The best any country can do is ensure its criminal investigations are professional and objective and its judicial procedures fairly test the evidence against the presumption of innocence.
The police and the judiciary need to re-examine their performance in the light of the Privy Council's decision, and recognise what they might have done better.
As for David Bain, he will no doubt be released on bail pending a decision on a retrial. If this is the end of his ordeal, no monetary award will be adequate compensation. According to Mr Karam he has used his years in jail to study and gain skills he can use outside.
And Mr Karam, too, can return to his own life forever honoured for his selfless, dogged, all-consuming commitment to justice.