Academics sourcing crime data from police are forced to sign a contract giving officers the power to "improve" research which shows "negative results" and then "veto" its publication.
A copy of the police-drawn contract given to academics wanting to access the publicly owned data shows those who do not comply will be placed on a blacklist which could extend to shutting off access to an entire university.
Conditions in the contract have been described as an attack on academic freedom and an affront to the Education Act's legal obligation on academic institutions to be a "critic and conscience of society".
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But they were also said to be an example of a growing wave of conditions placed on academics dealing with the government sphere because of concern research might expose politicians to criticism.
The contract was revealed during a clash between Police national headquarters and criminologist Dr Jarrod Gilbert, an academic at the University of Canterbury.
It came with a personal ban for Dr Gilbert - police told him he wasn't allowed to access data because of his "association with gangs". He is the author of the award-winning book Patched: The History of Gangs in New Zealand and lectures on the subject.
Dr Gilbert said he was astounded to be banned as a result of his research area and also over police attaching conditions to the release of data. The contract was a standard document he had since confirmed other academics had signed.
"I was astounded as much by what was in it but that other researchers had seen [the contract] and agreed to it. I'm astounded people haven't complained about these contracts before."
He said other researchers who worked in the field were gagged from speaking against it because of their need to access data for their work. "They are fearful ... if they make a noise they will no longer be able to get data."
The data sought by Dr Gilbert was for a government research project into "alcohol-related crime and proximity to premises with liquor licences in Christchurch". He was working with a team of five researchers - four with doctorates and two who are full professors.
"This was a project of enormous public importance which makes it even more astounding."
Dr Gilbert, who recently spoke at the Police Association annual conference, said the police rejection of his involvement for having an association with gangs was a nonsense. "I'm an academic who went into the field to do research."
Currently Canon Award Blogger of the Year, Dr Gilbert said: "I have from time to time been critical of police. I wonder if they think I am anti-police and this is a way of shutting me up."
Police deputy chief executive Mark Evans last night stood by the contract, saying it was necessary in cases where academics didn't understand or misrepresented information from police.
Labour's justice spokeswoman Jacinda Ardern said the police's apparent muzzling of Mr Gilbert was "extremely concerning" and he was owed an explanation and an apology.
She questioned whether his treatment was related to his past criticism of the Government's use of statistics, in particular his discovery that it had published inaccurate crime figures.
"Whether public interest in withholding the information outweighs the public interest in its disclosure is surely not the issue here," Ms Ardern said.
"What is at stake is the ability of researchers to carry out their work. Jarrod Gilbert's work is producing research with practical applications for our justice system."
NZ Tertiary Education Union president Dr Sandra Grey said the issue was an increasing problem and extended beyond police across the government sector.