My colleague Uri Friedman wrote about the impact of the Port Arthur massacre in the wake of the shooting in San Bernardino, California in 2015. He noted that, among other things, the Australian government “banned automatic and semiautomatic firearms, adopted new licensing requirements, established a national firearms registry, and instituted a 28-day waiting period for gun purchases. It also bought and destroyed more than 600,000 civilian-owned firearms, in a scheme that cost half a billion dollars and was funded by raising taxes.” The entire overhaul, Friedman pointed out, took just months to implement.

There was widespread opposition at the time to the legislation. Queensland and Tasmania, where the massacre occurred, were traditionally opposed to any gun-control legislation. The U.S. National Rifle Association had worked with gun-rights groups in the country to oppose any legislation that would make owning guns more difficult. Arguments against gun control ranged from the familiar “guns don’t kill people” to calling the legislation an insult to the vast majority of law-abiding gun owners. But proponents of gun control, who had long before the Port Arthur massacre called for restrictions on firearms ownership, pointed out that in Australia most people who committed gun violence had no criminal or psychiatric record. They added that it was pointless to compare the impact of an attacker with a semiautomatic gun with one brandishing a knife. As Simon Chapman, an Australian academic who was co-convener of the Australian Coalition for Gun Control from 1992 to 1997, wrote last year about the group’s successful advocacy for a gun registry: “One day during a TV interview in 1995, we said as we always did ‘We register cars. We register boats.’ But this time we added ‘We even register dogs. So what’s the problem in registering guns?’ It was the perfect sound bite. The next day a senior police official repeated the very same line on national television. From that point on, the air seemed to go right out of the gun lobby’s tires on that one.”

Over the years, advocates of the legislation have pointed to it evidence of successful gun control. As Friedman noted:

The number of mass shootings in Australia—defined as incidents in which a gunman killed five or more people other than himself, which is notably a higher casualty count than is generally applied for tallying mass shootings in the U.S.—dropped from 13 in the 18-year period before 1996 to zero after the Port Arthur massacre. Between 1995 and 2006, gun-related homicides and suicides in the country dropped by 59 percent and 65 percent, respectively, though these declines appear to have since leveled off. Two academics who have studied the impact of the reform initiative estimate that the gun-buyback program saves at least 200 lives each year, according to The New York Times.

Last year, on the 20th anniversary of the Port Arthur massacre, John Howard, the center-right leader whose government introduced and passed the legislation, said: “It is incontestable that gun-related homicides have fallen quite significantly in Australia, incontestable.” In the interview, he also cited a 74 percent decline in gun-involved suicide rates as evidence of the legislation working. But as the Australian Broadcasting Corporation pointed out: “While it is accurate for Mr Howard to assert that gun-related homicides and suicides have dropped since his reforms were implemented, there is more to it. Studies on the impacts of his reforms have come to varied conclusions and experts contacted by Fact Check said other factors would have influenced the drops, even though the reforms are likely to form part of the story.” The ABC report said “social support or government investment in social welfare are common factors that help depress crime rates and could be linked to the drop in firearm homicides and suicides.”