Australia's former prime minister explains how he helped solve mass shootings in his country

On April 29, 1996, 35 people were killed and 23 wounded when a 28-year-old Australian man opened fire in Port Arthur, Australia.

Twelve days later, the Australian government, under then-Prime Minister John Howard, proposed a sweeping set of gun laws known as the National Firearms Agreement.

It banned numerous types of semi-automatic rifles and shotguns, created a national firearms registration system, and permits for each gun purchase required a 28-day waiting period.

It was by no means an easy reform to pass, as Howard explained in a New York Times op-ed in 2013 - one month after the Sandy Hook shootings.

"After this wanton slaughter," Howard wrote, "I knew that I had to use the authority of my office to curb the possession and use of the type of weapons that killed 35 innocent people. I also knew it wouldn't be easy."

At the time, the Australian national government could only control gun import, but couldn't restrict gun sales or ownership. In order to pass the plan, Howard had to convince the country's states to each pass the gun control laws themselves.

In order to convince all the states to participate in supporting legislation, Howard threatened to hold a nationwide referendum to alter the Australian Constitution to grant the national government gun-control powers. Because a majority of the public was in favor of gun control, such a referendum would have passed, according to Howard.

The threat was never realized.

"In the end, we won the battle to change gun laws because there was majority support across Australia for banning certain weapons," Howard wrote.

As part of the agreement, the government introduced a one-time tax to finance a large-scale buyback program that took in 700,000 guns.

The legislation seems to have been a resounding success. Firearm homicides and suicides dropped, and gun massacres disappeared.

Australia has a radically different gun culture from the US. Though rural areas of Australia have a strong gun culture like the US, gun ownership is not considered a fundamental right. Close to 60% of Australians live in cities, where gun ownership is not as prevalent.

Australia's National Firearms Agreement would face strong opposition in the US and possibly even be considered unconstitutional.