Chief Censor David Shanks has disclosed that he received a death threat after banning the Christchurch mosque shooter's manifesto.
Shanks classified both the 17-minute video of the shootings, made by the shooter as he killed 51 people in two mosques, and the shooter's 74-page manifesto as "objectionable" a few days after the March 15 massacre.
He has disclosed in a TedX talk in Christchurch that he started to get anonymous emails after the decision.
"I started to get ammunition brochures sent into my inbox, and application forms for the American National Rifle Association," he said.
"I had one writer write to me saying they would shoot me in the face if I ever brought my censoring ways to the land of the free."
On the other hand, Shanks said one "big social media platform" thanked him saying that, by drawing a line declaring that sharing the video and the manifesto was illegal, he had made it easier for the platform to decide to remove the items.
He told the TedX audience that he watched the video of the killings quietly, "but inside I was screaming".
But he said he and his team had to apply what he called the three rules of censorship:
• First, the state doesn't get to make the call. The Office of Film and Literature Classification, which Shanks heads, is an independent Crown entity which applies the law independently of the Government.
• Second, "put freedom first - if you don't have to censor, then don't".
• And third, "only censor to prevent or limit harm".
Shanks, a lawyer, said he also had to consider the value of preserving records of historical events "to help us understand what has occurred".
But on balance, he banned both the video and the manifesto, called "The Great Replacement", because of the risk that they would inspire others to kill.
"We looked at this document [the manifesto] and we could see the exhortations to followers to kill, the rationale for killing unnamed people, for killing women and children," Shanks said.
Despite being banned in New Zealand, Shanks said the Christchurch killer's manifesto directly inspired gunmen who opened fire in a San Diego synagogue on April 27 and then in a Walmart store in El Paso, Texas, on August 3.
Shanks read the synagogue shooter's manifesto and it was "chillingly familiar".
"The writer was so inspired with the so-called Great Replacement manifesto," he said.
Shanks said there was a paradox at the heart of freedom of expression.
"The paradox is that if you really, truly value freedom of expression, if you value freedom of speech, then you have to set limits," he said.
"If you give a terrorist freedom of speech, they just use it as a weapon, and once people let that gain the upper hand, your freedoms, your rights - they will be the first things that they will crush."
The world needed to find a balance.
"It won't mean hamstringing reporters - getting in the way of those reporting the truth. We can all see that reporting the truth is more important now than ever," he said.
"But it will mean they report ethically and responsibly, that they don't fall into the trap of allowing their platform to be hijacked by killers."