Why are gun laws debated only after mass shootings?

New Zealand Prime Minister Jacinda Ardern announced on Monday that new gun laws would be drafted within days following Friday’s terrorist attacks that left at least 50 people dead at two mosques in the city of Christchurch.

“Within 10 days of this horrific act of terrorism we will have announced reforms which will, I believe, make our community safer,” Ardern said at a news conference after her cabinet reached, in principle, decisions on gun reform laws in the wake of New Zealand’s worst ever mass shooting. 

Deputy Prime Minister Winston Peters, who previously supported existing gun laws, also pointed that he will stand behind the change.

"The reality is that after 1pm on Friday, our world changed forever and so will our laws," Peters added.

David Tipple, the owner of gun shop Gun City, said the terrorist had legally bought four weapons and ammunition online from it between December 2017 and March 2018, but it did not sell him the high-powered weapon used in the massacre.

“The MSSA, military-style automatic, reportedly used by the alleged gunman was not purchased from Gun City. Gun City did not sell him an MSSA, only A-category firearms,” Tipple told a news conference in Christchurch. 

Under New Zealand gun laws, A-category weapons can be semi-automatic but limited to seven shots. Live-streamed video of a gunman in one of the mosques showed a semi-automatic weapon with a large magazine.

In the country with a population of five million, there are an estimated 1.5 million private weapons. Nearly one in three people has a private gun.

It's a common trend to debate gun ownership and revisit gun laws, after mass shootings or terror strikes are conducted against civilians in the developed world. For example, in Australia, some of the world’s toughest gun laws were introduced after its worst mass killing; the 1996 Port Arthur massacre in which a lone gunman killed 35 people using a semi-automatic AR-15, the same weapon used in the Christchurch massacre.

At least 17 students and staff were killed at Marjory Stoneman Douglas High School in Parkland, Florida, in the United States on February 14. The shooting reignited the debate over gun ownership in the US. 

Survivors of the Florida school gun massacre marched in Washington to demand reforms to gun laws. 

However, Florida state lawmakers only made small changes, raising the legal age for buying rifles and imposing a three-day waiting period on all firearms sales.

Despite tightening the gun laws across the US, these modifications cannot solve the increasing private ownership of military style weapons.

However, with the pressure of weapon companies, it is hard to impose strict laws against private armaments, especially in the US.

Last year, US President Donald Trump suggested that arming teachers and other school staff could help prevent future mass shootings.

There are limitations to gun control measures adopted by some states in the US. As long as other states maintain weak gun laws, people can simply cross state borders and buy firearms in gun-friendly districts. Therefore, stronger federal laws are needed, but the US is still far away from achieving that.