The Bain murder case has tarnished New Zealand's reputation for fair play and given the country a "black eye", former Canadian Supreme Court judge Ian Binnie says.
In 2011, Mr Binnie was asked by the New Zealand government to investigate compensating David Bain after the Dunedinite's conviction for killing five family members was quashed in 2009.
Mr Binnie went on to recommend compensation, a decision that was thrown out by the Justice Minister at the time, Judith Collins, after a peer review by Robert Fisher QC - a process Mr Binnie has described as "a stitch-up".
A report completed by retired Australian High Court Judge Ian Callinan in 2016 also concluded Mr Bain should not be compensated, but he was last year given an ex-gratia payment of $925,000.
Speaking to Kim Hill on RNZ's Saturday Morning, Mr Binnie said the process around Mr Bain's case was deeply unfair to the New Zealand public.
"New Zealand is famous, certainly in the sporting world and beyond, as people who believe in fair play, and I think what happened here is not fair play.
"And I say that regardless of whether you happen to view David Bain as guilty or innocent.
"I say there is a process, there should be fairness, there should be proper consideration, the same rules should apply, regardless of what report is being considered, and that didn't happen."
The Callinan report into the case had put the onus on Mr Bain to prove his innocence.
"While Ian Callinan and I differ sharply on the substance of what we take out of the evidence, that the methodology that he pursued has all the failings - if they are failings - that were alleged against me.
"That standard applied to me should be applied to Callinan. And why is it that when the application of the test runs in favour of Bain, the govt denies it, when it runs against Bain, the govt ignores it.
"There's a double standard and it all comes out against David Bain."
Mr Binnie said New Zealand appeared to be unwilling to admit that mistakes could have been made in the investigation.
"The police just have this view that they cannot be wrong. And everybody knows that they do make mistakes, we all make mistakes.
He said the process around the case had become political.
"What the inquiry should aim at is to get at the truth, not to be able to stand back and say 'well the police messed up an investigation, the evidence... a lot of it wasn't collected, a lot of it was destroyed, but over to you Mr Bain prove your innocence.
"What fairness lies in that?"
Mr Binnie said there had not been another case in his career where he found the process to be so deficient, and operated so unfairly.
"To the extent the case is known now, outside New Zealand, and is quite widely known, it's given New Zealand a black eye."
If the government had really believed that Mr Bain was responsible for the murders of his family members they would not have made the $925,000 ex-gratia payment, he said.