The decision to charge the accused Christchurch gunman under the Terrorism Suppression Act risks giving the accused a "megaphone" to spout his white supremacist views, a law expert says.

University of Auckland Law Professor Bill Hodge told Newstalk ZB's Heather du Plessis-Allan the charge, laid on May 21 by police, was risky as it had never been applied before in New Zealand.

It would give the accused the platform he wanted to read his manifesto, Hodge said.

"We're stepping into unknown territory," he said. "Murder is cut and dried, every law student knows the definition, every law student knows the act and the mentality whereas this has never been tested before in New Zealand."


The accused had already been charged with 51 counts of murder and 40 of attempted murder, and a terrorism charge would not add to his sentence, Hodge said.

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He called the terror charge a "feelgood" move. It had been laid because "it makes you feel, ah yes, he's a terrorist, yes it's hate crime, we want to get him for that".

"But my point is this will give him a platform. He will say 'I'm not a terrorist, I'm a patriot, don't give me a conviction, give me a medal. I'm here to help the civilian population, not terrorise them', and so on. He'll get to read his manifesto.

"This gives him a megaphone. That is, the charge of terrorism doesn't have a definition that's been approved by the courts - we've never used it before - so he will get to give evidence on that point."

Only Section 6A of the Terrorism Suppression Act was likely to apply to the accused shooter, Hodge said - the rest of the act referred to actions such as financing terror overseas or recruiting others to join a terrorist group.