Labour MPs erupted in protest at an annual review of the police after a National MP suggested the Police Commissioner was complicit in "criminalising thousands of law-abiding New Zealanders".
National's police spokesperson Brett Hudson probed the outgoing Police Commissioner, Mike Bush, about progress on the Government's gun buyback amnesty scheme.
Hudson pushed back against Bush's claim that the buyback would be a success, because there "will have been ample opportunity for good, honest people to bring their firearms in and surrender them".
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Hudson asked the Police Commissioner if he was saying that the vast majority of people handing their guns are good, law-abiding New Zealanders.
"The attitude you're displaying today... is you're more than happy to criminalise thousands of otherwise law-abiding New Zealanders because the Government got the buyback scheme wrong and they didn't listen to advice."
Hudson's comments were met with gasps from Labour MPs on the other side of the Justice Select Committee, including Ginny Andersen and Clare Curran.
"That's out of order," one of them yelled, as another labelled his comments "ridiculous".
Hudson told Newshub the Labour MPs interjected to "try to stop National highlighting the failings of the Police Minister".
"Particularly how he is criminalising thousands of otherwise law-abiding New Zealanders because he refused to heed expert advice about his failing buyback scheme."
Hudson pointed to a report by the consulting firm KPMG which recommended three buyback scheme options, and the Government went with an option it said would result in lower compliance.
The option KPMG put forward with higher expected compliance would have been to have one price for all models of firearms, regardless of condition - but it would have been more expensive.
It also noted how there hadn't been enough time to design the buyback scheme, noting a "number of limitations on our ability to draw clear conclusions on how various pricing options would perform".
One of the main difficulties in designing the buyback was that there is no definitive number of firearms in New Zealand because there is no gun register.
"We have no way of knowing," Bush said.
Hudson asked the Police Commissioner: "Why have you not paused to say, maybe we should change something or recommend the Government change something in the scheme, to increase compliance?"
Bush replied: "We have done everything possible to ensure people can comply."
Bush also pushed back on criticism of the buyback after gang leaders publicly said they won't be handing in their illegal firearms.
He said police have spoken to "influential gang leaders".
"We are hopeful that gangs will listen... We can't compel them to... We can simply try and create the right environment."
Bush revealed more than 100 gang leaders had been contacted by the police in an effort to convince them to hand in their illegal guns.
Police Minister Stuart Nash sent out a reminder last week that time is running out for gun owners to take part in the firearms amnesty and buyback, which ends on 20 December.
He said since the first collection event on 13 July in Christchurch, more than 19,000 people have walked out the door with more than $62 million in payments.
There have been almost 350 collection events, some held publicly and some held privately to suit gun clubs and hunting groups.
Bush said about 67 percent of the items handed in so far are military style semi-automatics (MSSAs).
Police have estimated at least 14,000 guns around the country are banned under the new legislation that came into effect following the March 15 Christchurch terror attack.
An MSSA was used by the shooter to kill 51 people.
The total number of all weapons in New Zealand, both lawful and prohibited, is estimated to be approximately 1.2-1.5 million.
The Government has set aside more than $200 million to buy back weapons.