(CNN) After any mass shooting, whether it's the recent Orlando massacre or the terror at a Charleston church or the killings in Newtown, Connecticut, one statistic is often cited: Australia has had zero mass shootings in two decades, while America faces frequent bloodshed.
Indeed, Australia has long been referenced in the ongoing debate over how to stop mass shootings in the United States.
After a shooting at Umpqua Community College in Oregon in October, President Barack Obama said, "We know that other countries, in response to one mass shooting, have been able to craft laws that almost eliminate mass shootings. Friends of ours, allies of ours -- Great Britain, Australia, countries like ours. So we know there are ways to prevent it."
A study published in the Journal of the American Medical Association on Wednesday not only offers a detailed timeline of Australia's reduction in mass violence, it confirms that the country experienced a rapid decline in firearm homicides and suicides after enacting gun law reforms in 1996.
"The results are clear," said Simon Chapman, a professor at the University of Sydney's School of Public Health and lead author of the study.
"Gun deaths are a problem amenable to reduction like any other public health problem," he said. "International differences in rates between countries show this. The United States has the worst record of gun deaths of any [Organisation for Economic Co-Operation and Development] nation, exceeded only by that in chaotic nations with massive law and order problems."
For the study, researchers in Sydney examined gun-related incidents and death reports from the Australian Bureau of Statics and news articles, dated from 1979 to 2013. They determined how many fatal mass shootings, gun-related suicides and homicides occurred during that time period and analyzed the data.
The researchers noticed that after the enactment of nationwide gun law reform in May 1996, there were no mass shootings in Australia. The researchers defined mass fatal shootings as those with five or more victims killed, not including the perpetrator. (U.S. statutes define a "mass killing" as an incident resulting in three or more deaths. The commonly accepted definition -- the one the FBI used up to 2013 -- is a shooting that killed four or more people.)
Also in the years that followed, gun suicides declined by an average of 4.8% per year, and gun-related homicides declined by an average of 5.5% per year.
The data show a correlation between the gun law reforms and gun violence. But the researchers noted in their study that non-gun-related suicides and homicides also went down. So overall, the data alone weren't enough to provide a direct causation.
But if gun laws were reformed in the United States, where nearly a third of the world's mass shootings took place from 1966 to 2012, could we see a decline in violence?
Johns Hopkins Bloomberg School of Public Health professor Daniel Webster wrote an editorial accompanying the study, also published in the Journal of the American Medical Association. "Political, cultural, and legal challenges make it highly unlikely that the United States would implement comparable policies," he wrote. "Yet the experience in Australia over the past two decades ... provides a useful example of how a nation can come together to forge life-saving policies despite political and cultural divides."
So, it's difficult to predict what would happen, especially since gun ownership and gun violence are at a much larger scale in the United States than Down Under. However, there's no question that we would see a drop in the frequency of mass homicides, according to David Hemenway, professor of health policy at the Harvard School of Public Health, who was not involved in the study.
"If we had stronger laws, we'd have fewer gun problems," Hemenway said.
"But the key thing in Australia is that this was done by a conservative leader," he added. "One would have hoped that after the Newtown or Orlando killings that a conservative legislator would have stepped up and said 'we have to do something,' but they really haven't."
Australia implemented gun law reforms after a lone gunman killed 35 people at Port Arthur, a historic tourist site in Tasmania, on April 28, 1996. Under the leadership of conservative Prime Minister John Howard, rapid-fire rifles and shotguns were banned across the country, gun owner licensing was tightened, and a national buyback program was implemented to encourage firearms owners and dealers to surrender their weapons.
"It's rare to see such a strong effect from an intervention in any field of public health, let alone firearm violence," said Garen Wintemute, an emergency medicine physician at the University of California, Davis, who was not involved in the study. "This intervention targeted mass shootings. In the pre-intervention period, there were 13 mass shootings, and in the post-intervention period, there were none."
Previous studies also have analyzed how these gun law reforms affected violence in Australia, but the new research seems to be the most comprehensive yet, said Wintemute, a gun violence expert.
"This is arguably the strongest study in the literature on the effect that policies addressing specific types of firearms might have on firearm violence," he said. "Mass shootings account for less than 1% of fatal firearm violence in the United States. Policies here should address firearm violence generally, with mass shootings as a subset of that violence."
The National Rifle Association, however, disagrees.
In a statement to CNN, NRA spokesperson Jennifer Baker said, in part, "The study did not find a statistically valid relationship between the gun 'reforms' and the homicide rate and concludes that the impact of the gun 'reforms' cannot be estimated because suicides and homicides from all causes began decreasing before the gun ban and confiscation program was in place."