A Queen's Counsel who helped write the Thorp Report says lives would have saved in the Christchurch terror attack if semi-automatic weapons were banned as the inquiry recommended.
Simon Mount, QC, worked alongside Sir Thomas Thorp on the government inquiry which made 60 recommendations in 1997 to tighten gun control in New Zealand.
One of those recommendations was to ban semi-automatic firearms - something Australia did in 1996 following the Port Arthur massacre which claimed the lives of 35 people.
But the Thorp Report was largely ignored and the National Government only partially introduced one of the recommendations in 1999.
Mount said even the proposed loose form of registration introduced in the bill was vigorously opposed by gun lobbyists and the legislation was not passed.
"Tragically, I believe if the Thorp recommendations had been implemented in 1997, the Christchurch attacker would not have been able to obtain the semi-automatic weapons he used in this country," said Mount.
While the alleged killer's manifesto talked "implausibly" about using alternative measures, like a hammer and wooden shield, Mount said the reality was Military Style Semi Automatics (MSSA) are the "weapon of choice" for mass killings.
"Without access to semi-automatics and ammunition, I believe the attack would not have occurred, or would at least have been made much more difficult and less deadly."
Prime Minister Jacinda Ardern says New Zealand's gun laws will change after 50 people were shot and killed while praying at their mosques in Christchurch on Friday.
The alleged shooter obtained a standard A-Category licence and was able to legally purchase an AR-15 semi-automatic rifle.
These weapons - used in mass shootings in San Bernadino, Sandy Hook and Las Vegas - can be easily converted to a MSSA weapon simply by inserting a high-capacity magazine.
These magazines can hold 30, 75 or even 100 rounds.
Sir Thomas recommended banning semi-automatics and said the value of MSSA weapons in hunting and target practice was limited.
"I am satisfied that the potential consequences of MSSA misuse clearly outweigh any benefit to society in permitting their ownership."
Following the Thorp Report, Mount said New Zealand's gun lobby "mobilised very effectively" to pressure the National Government.
"I am not an expert on the current state of the gun lobby in New Zealand," said Mount. "
What we found at the time was that most gun owners are sensible, law-abiding New Zealanders who support common sense regulation," said Mount.
But others held quite extreme political views and opposed almost any form of regulation, said Mount, as well as well-organised firearms groups which mobilised to oppose reform through direct pressure on politicians.
Mount was optimistic the current Government would now take meaningful action.
"As with everyone else, my first thoughts at the moment are for the victims of the attack. But I certainly hope that consideration is finally given to implementing the reforms Sir Thomas proposed in 1997."
The Prime Minister has said the gun lobby in New Zealand will not dilute the planned crackdown on firearms. She said the Cabinet had agreed "in principle" and will seek cross-party support.
Deputy Prime Minister Winston Peters, whose party New Zealand First is seen as the strongest advocate of the gun lobby in Parliament, is now also behind the reform.
"The reality is though is that after 1pm on the 15th of March, our world changed forever and so will some of our laws," Peters has said.
There was no place in the upcoming debate for the radical gun lobby, said Police Association president Chris Cahill.
"The bitter irony with this alleged perpetrator in Christchurch is he would not have been able to buy the weapons he had in his home country of Australia," Cahill said after the PM announced gun laws would change.
"Immediately after the Port Arthur massacre in 1996 the then Prime Minister John Howard acted swiftly to ban semi-automatic weapons and Australians were with him."
Thirty-five people were murdered by Martin Bryant, who was firing two MSSA firearms, in Tasmania.
Just months after taking office, Howard moved quickly to push for new laws which banned automatic and semi-automatic weapons, established a comprehensive national firearm registration, and an amnesty period for prohibited and unregistered weapons to be surrendered.
In the "buy-back" scheme, the Australian government purchased 700,000 firearms.
The attempts to reform gun laws in Australia were still controversial.
Hundreds of thousands of people protested the campaign; Howard even wore a bullet-proof vest when speaking to an angry crowd.
However, the new laws were changed and remain Howard's defining legacy.