The number of young Māori coming before the courts rose 9 percent last year, according to research carried out by a group of high school students.
The work has been completed by St Thomas' in Christchurch as part of an annual project - the National Youth Custody Index - which uses the Official Information Act to compile a snapshot of how well the justice system is doing in dealing with young people.
The study - released at the Nga Hau E Wha National marae today - looked at how those aged between 10 and 16 are fairing when they fall foul of the law.
It found the number of children charged in court increased by 6 percent last year, compared to the year before.
While the number of young European people in court was down 1 percent, there has been a 9 percent rise for Māori over the 12 months.
Student Te Aotahi Rice-Edwards said it was not acceptable that most young people who came before the courts were Māori.
"It resonates with me because I am Māori first of all, but also because I hate to know that other young Māori youth have been in those situations. And it's 64 percent and it shouldn't be that high and the number is only growing every year."
The data-rich research relied on responses from government departments and the police to Official Information Act requests.
It has been carried out for the past four years and most have been forthcoming with requested information.
But, for a fourth year running, the Ministry of Social Development - which oversees the Ministry for Vulnerable Children - has failed to respond by the deadline for the findings to be published.
Chief ombudsman Judge Peter Boshier, who was at the launch, said that was not good enough.
"It's pretty sad that once again that one of our leading agencies has failed to comply with its statutory obligation. And yet another one, the New Zealand police has in my time as chief ombudsman raised the bar to a level where it is complying with this Act in spirit and in form. It can be done and you are entitled to better."
He said the Official Information Act needed to be treated with greater respect.
St Thomas' principal Christine O'Brien said having struggled initially to get agencies to take them seriously, her boys were now being engaged with in a meaningful way.
"With the offer from the chief ombudsman for the involvement of his office this year, that's really enhanced the quality of the information. So for example the police have been excellent, Corrections have been very good, the ongoing disappointment is the failure of the Ministry of Social Development."
In a statement, the Ministry of Social Development said the information the school asked for took too long for it to compile within the statutory timeframe.
It said it asked the school to refine its questions but the school declined to do this.
The Ministry said it was continuing to work on a response.