Legal experts hope the unprecedented sentence handed down to the Christchurch terrorist on Thursday won't set a legal precedent - because that would mean a repeat of what Prime Minister Jacinda Ardern described as New Zealand's "darkest day".
The Australian-born gunman who killed 51 and injured another 40 on March 15, 2019, will spend the rest of his life behind bars, with no chance of parole. It's the toughest sentence available under present New Zealand law, and the first time it's ever been used.
University of Waikato law professor Al Gillespie told Newshub when the judge read out the sentence, he was relieved.
"This is an unprecedented sentence for an unprecedented crime, and the judge got it completely correct."
There was concern among legal experts the killer's guilty plea, sparing the survivors and their families the ordeal of a trial, would be considered a mitigating factor in sentencing.
"He pleaded guilty, and [the judge] effectively had to discount that consideration against all the other aggravating factors - the act of terrorism, the hatred, the weapon, the crime itself," said Prof Gillespie.
"He had to weigh it very carefully - if you effectively say you don't get anything for pleading guilty, you could create a disincentive. But in this instance the sheer magnitude of the horror means everything else gets pushed to one side."
Prof Gillespie said there were also signs "at the end" the terrorist had started to show remorse.
"It certainly did not seem sincere. He even agreed himself with the sentence."
Sentencing offenders to life without parole became possible with the passing of the Sentencing and Parole Reform Act in 2010. It was backed by National and ACT, and opposed by Labour, the Greens and the Māori Party (who were in coalition with National at the time).
"We expect these cases to be rare, but, in the worst cases, the families of the victims - and the public - have a right to know that the offender will not be released on parole," then-Justice Minister Simon Power said in 2009 when he introduced the Bill including the change.
In usual circumstances, the first-ever use of a sentence would set a precedent for how it could be used in the future.
"The furthest we've ever got previously was someone had 30 years without parole - what we've done now is we've gone beyond that," said Prof Gillespie. "It's an exceptional sentence, but in this circumstance it's the correct one. Anything less would have caused outrage."
But University of Otago's Andrew Geddis says its value as a precedent will be "quite limited" - or he at least hopes that's the case.
"This was such an unprecedented event. It's hard to imagine anything that will come close."
He agreed with Prof Gillespie that the sheer horror of what the terrorist did outweighed all other considerations.
"The absolutely horrendous nature of the crime made the need to denounce that crime so paramount. As the judge said, even spending the rest of his life in jail is not going to be enough to denounce just how hideous these crimes were."
Despite opposing the law change in 2010, Labour's David Parker said on Friday he backed the stiff sentence.
"It's fair. It's imposed an appropriate sentence here - can't think of worse case, can you?"
National's Simon Bridges, a former Crown prosecutor and Associate Minister of Justice, said it was the only sentence "you could envisage in this case", and hoped messages of forgiveness from some of the survivors and family members would "stick with the killer for the rest of his days".
The terrorist was transferred to New Zealand's most secure prison, the maximum security facility at Auckland's Paremoremo, on Friday morning. He will spend the rest of his life there.