Roy Wade: Only custom, not law, that's preventing third trial of Malcolm Rewa

• Roy Wade is a retired District Court judge.

The police now accept Teina Pora is innocent but say Malcolm Rewa cannot be prosecuted because the juries in his two earlier trials failed to reach a verdict, resulting in the Solicitor General issuing a stay of proceedings.

But there's no law that says a third trial can't happen. It is simply custom, not law. And it would not be unprecedented.

In February 1994 father and son Eugene and Gene Thomas were murdered in their central Wellington office. A businessman who owed them a large sum of money, John Barlow, was charged with their murder. Two trials resulted in hung juries but a third trial was allowed which resulted in a guilty verdict in November 1995 and a sentence of life imprisonment.

Barlow's subsequent appeals to the Court of Appeal and the Privy Council were both dismissed.

It is said no new evidence has come to light in the Susan Burdett case but that is at least arguably incorrect. The principal reason that must have troubled the jury in the two Rewa trials was, surely, how can we be sure it was Rewa who was the murderer when we know Teina Pora confessed to it, because no one in their right mind would make a false confession?

The new evidence is that (so the Privy Council confirmed) Teina Pora was not in his right mind at the time of the confessions because he was suffering from foetal alcohol spectrum disorder that made him prone to false confessions.

As the Privy Council put it in its judgment: "The combination of Pora's frequently contradictory and often implausible confessions and the recent diagnosis of his FASD leads to only one possible conclusion and that is that reliance on his confessions gives rise to a risk of a miscarriage of justice.

"On that account, his convictions must be quashed."

So the recent diagnosis is surely fresh evidence?

The Crown Law Office discovered a very few days ago that the public of New Zealand rise up in anger when they believe someone has been allowed to get away with murder. Malcolm Rewa is eligible for release within a couple of years, unless he is meanwhile convicted of Susan Burdett's murder, and I believe another uproar is likely unless it has been demonstrated that a further trial is impossible. As I have said before, justice must not only be done, it must manifestly and undoubtedly be seen to be done.

Again to quote from the judgment of the Privy Council: "The man who raped Ms Burdett was undoubtedly Malcolm Rewa. That she was killed at the time that she was raped is not open to doubt.

"Unless Pora was present at the time of the rape he could not be implicated in Ms Burdett's murder."

Now we know Pora was certainly not present. Never mind that a Crown Law expert thinks the court may reject an application to lift the stay of proceedings. It was Crown Law which granted that stay in the first place.

Make the application for a third trial and say "we got it wrong". If the court says no, at least we will know the Crown has done its best. In grave cases such as this, the public interest demands nothing less.