The case is set to be reopened in the High Court. Photo: RNZ / Simon Rogers
A justice advocacy organisation says a mistake that sent a 15-year-old boy to an adult prison in 2001 was avoidable.
The Criminal Cases Review Commission is instructing the High Court to reopen the case, because people under 16 cannot be sent to prison except for serious offending - but an incorrect birth date on documents meant the court thought the boy, referred to as Mr G, was 17.
However, JustSpeak executive director Aphiphany Forward-Taua said he was too young to be in an adult prison, regardless of whether he was 15 or 17.
"There's no doubt in our minds that the trajectory of his life and the opportunities available to him would have been adversely affected and that there was probably some deprivation that he's experienced because of these convictions."
The referral comes after an earlier appeal was dismissed by the High Court.
It is the first referral the independent body has made since it was set up two-and-a-half years ago.
Investigation manager Tim McKinnel said while other cases, including where people were currently in prison, might be higher priority, this was the first to be referred because the investigation was fairly straightforward.
"Not as straightforward as you might think to establish somebody's age, but the focus is very narrow here," he said.
"Most of our investigations aren't that narrow and they take more time. Once we'd got to the conclusion of this investigation, it would have been artificial to delay it."
Chief Commissioner Colin Carruthers said Mr G came to New Zealand as a refugee from Somalia when he was seven, and left school when he was 13, unable to read or write in English.
Carruthers described the referral as a "watershed moment" and said it was clear authorities failed Mr G.
"One would have expected a police investigation to be thorough-going before material was put before the district court indicating he was 17 years of age."
The case illustrated why the commission was set up, he said, because a mistake was made and went undetected.
The referral leaves the commission with 214 open files.
Chief executive Parekāwhia McLean said the commission had received a deluge of applications.
With only 23 staff members - of which five were investigators and four were legal experts, more funding was needed, McLean said.
"We certainly have made the case given what was anticipated and planned at the establishment of Te Kahui and the demand and what we're now receiving," she said.
"Ultimately that is a decision for the minister to make."
The commission was confident the court would back its findings regarding Mr G's case, and said it would not have made the referral otherwise.
The matter is likely to be heard early next year.