"It's a little unusual to have someone with a prosecution background to be still concerned about the prospect of wrongful convictions."
So says Canadian Bruce MacFarlane, QC, a former deputy justice minister for the province of Manitoba. Most of his career, his job was to lock up offenders. For 15 years as a young prosecutor, he was in court just about every day and later ran the whole process as the Justice Department's director of federal prosecutions.
He slept well at nights until, under his watch, DNA proved that David Milgaard was innocent of a rape and murder for which he spent 23 years in jail. That sparked a royal commission.
The evolution of DNA technology enabled a profile to be detected in a dried semen sample. As well as clear Milgaard, it identified the real offender.
"At the time we were at a stage where the attitude was that wrongful convictions don't really happen. Those raising their voices about it were wrong because we had so many safeguards in the system. That was the general atmosphere. DNA changed the picture."
The Milgaard case was the beginning for MacFarlane and for Canada of an uncomfortable realisation that there are systemic factors at work, which are just as applicable to New Zealand.
Wrongful convictions in Canada have resulted in six commissions of inquiry. The last time New Zealand held one on the issue was 39 years ago, into the Arthur Allan Thomas case. It concluded that evidence was planted.
Teina Pora, David Dougherty, Aaron Farmer and David Bain have since been found to have been wrongfully convicted and three of them have received government apologies and compensation.
MacFarlane, who spoke to the Herald while in New Zealand this month for an event hosted by a group called Justice For All, wrote the briefs for two of Canada's inquiries.
One recurring theme was the reliance on unsavoury witnesses. In two of the cases examined, multiple jailhouse informants were called. "They lied, leading directly to a miscarriage of justice," says MacFarlane.
From Arthur Allan Thomas to Teina Pora - the problem with prison witnesses
One was the Sophonow inquiry. Thomas Sophonow was convicted after three trials of the murder of a doughnut-shop worker before finally being acquitted having spent four years in jail.
"At the time of the murder, he was about 16km away giving Christmas gifts to children at a hospital. That's what he was doing. The jury just didn't believe him.
"Sophonow concerned me because of the alibi problem, the eyewitness problem - the eyewitnesses were simply wrong - and the jailhouse informants."
Eleven prisoners claimed Sophonow confessed. The prosecutor selected three to put before the jury, including one who had a conviction for perjury. "All three lied."
As a result, protocols around using such witnesses in Manitoba have been tightened - MacFarlane calls it "a chokehold" - and they have "all but disappeared from Canadian courtrooms".
The flow-on from the inquiries led to a culture change, says MacFarlane, who also examined how it is that prosecutors could make such distorted decisions.
"It is truly a culture change. I am not just paying lip service to it." The old attitude was if there's enough to get it into court, let the jury decide. "We have moved way beyond that now." Subsequently, the rate of miscarriages coming to light has dropped away, he says.
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Previously, jailhouse informants would be called if there was a ring of truth and eyewitness identification was regarded as really good evidence. "You've got a witness in court who is pointing at the accused saying that's the guy who raped me. It's very powerful."
When Canada looked around the Western world, it found common problems across countries with different legal and political systems. "How is that? There is only one answer and that is these are systemic causes, they're not one-offs, which is very frightening for me … That includes New Zealand."
In New Zealand, mistaken eyewitness identification led to the wrongful conviction of David Dougherty for the abduction and rape of an 11-year-old girl, and a jailhouse witness lied in the retrial of Teina Pora.
Prison witnesses are often called in New Zealand, including in the trials of David Tamihere, Scott Watson and Mark Lundy.
One of three such witnesses who testified against Tamihere was convicted in 2017 of perjury in a private prosecution.
The Crown has never charged a jailhouse witness with perjury. The police do not keep records about their use and the Ministry of Justice does not have a detailed protocol regarding them.
While juries are good at many things, says MacFarlane, they are not good at sussing out jailhouse informants, simply because the prison world is so foreign.
"Those of us on the outside don't really understand how life is in jail. It's all about tricking people, getting privileges of some sort, anything to soften the blow of being in jail. The other point is that they have a lot of time on their hands, time to map out a strategy."
Justice Minister Andrew Little was among those who, after the perjury conviction of Roberto Conchie Harris in the Tamihere case, thought it was time to review the use of jailhouse witnesses. "We've seen so many cases now where jailhouse snitches have proven to be, frankly, abject liars," he told the Herald but has left it up to the judgment of prosecutors and police.
MacFarlane was to meet with Little and said he would answer the minister's questions frankly, despite a reluctance as a foreigner to tell another country how to suck eggs.
However, he happily gives this advice: "Where a serious error was made in a case … where a person is shown to be factually innocent, government should seriously consider a public inquiry to find out what went wrong and try to learn from that.
"It's vital the public has confidence in the criminal justice system and it is easy to lose. That's why Canada had six commissions of inquiries. We needed a public ventilation of the case so the public understood what had happened."
Faulty science and false confessions are emerging problems internationally while in Canada there is a growing focus on wrongful convictions of indigenous people.
"There is a brewing storm in that area because indigenous people often just accept the decision and don't challenge it. I think the same issue lies in New Zealand."
MacFarlane says he would like to think there could be a similar culture shift in New Zealand. "But I do concede that the Government feels pushed by public views and the Canadian public right now is outraged by wrongful convictions."
In New Zealand, Sir Thomas Thorp, a former High Court judge was the first to warn of systemic problems in New Zealand, predicting in 2005 that there was likely to be 20 people in jail wrongly convicted of serious crimes.
Thorp, who died last year, studied other countries and recommended New Zealand look at reforms made in Canada and set up a state-funded but independent Criminal Cases Review Commission based on the UK model, which can refer cases back to the courts.
A bill to replace the royal prerogative of mercy process (run within the Justice Ministry) with such a commission is currently at its second reading.
Canada's reforms have not included a commission but MacFarlane says his view of them has evolved.
"At an earlier stage of my career, I didn't think one was necessary. I am leaning towards the need for a commission now."
While the appeal system can work well, an independent commission would give the public confidence in the process "so long as it is properly funded and, critically, has the right people to do the analysis".
New Zealand Wrongful Convictions:
• Teina Pora. Twice convicted of rape and murder of Susan Burdett. Served 20 years. Convictions quashed by the Privy Council in 2015. Received compensation of $3.5 million and a government apology. Factors included evidence by a jailhouse informant, paid witnesses, tunnel vision.
• Aaron Farmer. Convicted of raping a 22-year-old woman in Christchurch. Retrial ordered because alibi evidence was not put to the jury. Before the retrial took place, DNA evidence ruled out Farmer and the Crown withdrew the case. Farmer, who spent two years in jail, received $351,000 in compensation and a government apology in 2011. Factors included police misconduct.
• David Bain. Convicted of the murders of his parents and three siblings, in Dunedin. Convicted in 1995, overturned in 2007 by the Privy Council, acquitted at a retrial in 2009. Served 13 years in prison. Defence argued that the real culprit was his father and that is was murder/suicide. The Government did not pay compensation but an ex gratia payment of $950,000 was made on condition Bain agreed to stop all further legal action.
• David Dougherty. Convicted of the abduction and rape of an 11-year-old girl, in Auckland. Acquitted in 1997 after serving three years in jail when DNA evidence ruled him out and identified the real culprit. Paid $800,000 in compensation and received a government apology. Factors involved mistaken identification by the victim.
• Arthur Allan Thomas. Convicted of the murders of Jeannette and Harvey Crewe, in Waikato. He spent nine years in jail, was given royal pardon, and awarded $1 million in compensation. A Royal Commission of Inquiry in 1980 concluded that evidence was planted.
Common factors in wrongful convictions:
Public and media pressure
Police or prosecutorial misconduct