What a New Gun-Control Study Can — and Can’t — Tell Us About Mass Shootings


The American conversation about mass shootings is excruciating and circular because there is no possible universe in which our lawmakers will tighten gun control in a meaningful way anytime soon. Among advocates for stronger restrictions on who can buy guns — or at least the most deadly ones — the best hope, for now, is to simply keep building the case and amping up the pressure, in the hopes that some sort of tipping point will eventually be reached.

One way to do that is to highlight gun-control research from countries that have taken significant action on this front. One important such example was just published in the Journal of the American Medical Association, or JAMA, in an article by Simon Chapman and Philip Alpers of the University of Sydney School of Public Health, and Michael Jones of Macquarie University (also in Sydney). That article, and an accompanying editorial by Daniel Webster of the Johns Hopkins Bloomberg School of Public Health, take a nuanced, deep look at the impact of Australia’s famous gun-control law. And while the results are open to interpretation because of the statistical difficulty of sussing out the effects of any one law — and, as I’ll explain, it’s particularly difficult in the case of Australia — they suggest that a lot of lives would be saved if the Republican Party ever changed its tune and was willing to look Down Under for guidance on our gun problem.

A bit of background is helpful here. Australia’s gun-control law, the 1996 National Firearms Agreement and Buyback Program, or NFA, was passed in 1996 in the wake of the so-called Port Arthur Massacre, in which a 28-year-old man with intellectual disabilities killed 35 people and wounded 23 other in Tasmania. In shocked response to that act, the country’s lawmakers quickly came together across partisan lines and, led by conservative Prime Minister John Howard, passed the NFA.

That law, as Margaret Hartman explained in a great rundown of the Australian and British approaches to gun control, “included a ban on many types of semi-automatic, self-loading rifles and shotguns. Each gun required a separate permit with a 28-day waiting period, and Australia created a national firearms registration system. … Firearm owners had to be 18, complete a safety course, and have a ‘genuine reason’ for owning a gun, such as sport shooting, hunting, or occupational requirements (‘personal protection’ did not count as a legitimate reason). Licenses expired every five years, and could be revoked if police found ‘reliable evidence of a mental or physical condition which would render the applicant unsuitable for owning, possessing or using a firearm.’” And, as the name of the act implies, it included a program to buy back now-outlawed weapons at market value.

The NFA had a seismic effect on Australia’s gun landscape. As the authors point out, “the proportion of Australian households reporting private gun ownership declined by 75% between 1988 and 2005.” Chapman and his colleagues’ main goal, then, was to use Australia’s crime and mortality statistics to find out what effects this massive reduction had on the stuff gun control is supposed to address: homicides, suicides, and mass shootings.

Let’s start with what we can’t say their study shows. We can’t say, definitively, that it shows that the NFA “worked” at reducing the rate of firearm deaths in Australia. That’s because the passage of the law happened at a time when these sorts of violent acts were already on the decline in Australia. And specifically, while “[t]here was a more rapid firearm deaths between 1997 and 2013 compared with before 1997” — meaning after the law passed, firearm deaths dropped faster than they already had been — there was “also a decline in total nonfirearm suicide and homicide deaths of a greater magnitude. Because of this, it is not possible to determine whether the change in firearm deaths can be attributed to the gun law reforms.”

This is a common problem in evaluating public policy; there’s always other stuff going on. In other words, even as you tweak one variable of interest — in this case, Australia’s gun laws — there are a zillion other things constantly changing that also affect the outcome of interest: the rate of violent deaths. There’s often just no easy way to explain, decisively, exactly how much of a trend can be traced back to a given act.

None of this is made any easier to figure out by the fact that Australia has, for decades, had a pretty low homicide rate — between 1993 and 2007, for example, the number has fluctuated around 300 total murders per year (there are American cities that have that many in a year). And last year, Australia hit a record-low rate of 1.1 murder victims per 100,000 residents, which is about a quarter of the American rate. If you sort the list of all the countries in the world by murder rate, in fact (yes, yes, Wikipedia, I know — but the article is well-cited and there isn’t a better online table that I can find), you can see that Australia is one of the very safest countries in the world, at 185 out of 218 (the U.S. is 107, lumped in, depressingly and unsurprisingly, with a lot of countries way less stable and wealthy than our own).

So, in a society that already doesn’t do a lot of killing, it can sometimes be even tougher to explain increases and especially decreases (since there isn’t that much room for them to go down) in the murder rate. In this case, that may be forcing researchers into a more cautious interpretation of the data than is warranted. “The main reason there is uncertainty around the effect of Australia’s NFA on firearm homicides is that their rates are so incredibly low and a shooting here or there makes for big swings in percentage terms,” explained Webster in an email. “But they have gotten to a level where being murdered with a gun is an incredibly rare event. I suspect that has something to do with how guns are regulated in Australia.” He also noted that Australia, like the U.S., had state-by-state (and territory-by-territory) differences in gun laws before the NFA was passed, and that “prior studies of the effects of Australia’s NFA demonstrated that the states and territories that experienced the largest changes in their gun regulations (the NFA brought the less strict regulating places into line with the most restrictive places with respect to who is eligible to have guns, how they must be stored, etc.) [link added by me]” also saw the largest reductions in murder gun-death rates.

Whatever the overall impact of the NFA on Australia’s already-low rate of gun deaths, there is a strong case, according to Chapman, his co-authors, and Webster, that the NFA reduced mass shootings in Australia, which they define as shootings involving five victims or more, excluding the perpetrator when he is killed (there’s no universally accepted definition of the term). In fact, since the law’s enactment, there hasn’t been a single mass shooting in Australia. As Webster points out in his editorial, this doesn’t make for a slam-dunk case that the law reduced mass shootings, but it does make for a strong circumstantial one, partly because of what we know about mass shootings in the U.S.:

What is most clear from the current study is that Australia’s NFA coincided with an elimination of mass killings with firearms. It is difficult to pinpoint precisely which aspect of the policy contributed to this success, but the substantial reduction in the population’s exposure to semiautomatic long guns capable of accepting large-capacity magazines (LCMs) for ammunition is likely to have been key. Examinations of fatal mass shootings in the United States have found that when assault weapons or pistols with LCMs are used in these shootings, the number of victims shot is about 2.5 times higher than in mass shootings with other firearms.

In other words: You can’t prove that the ban was the reason mass shootings stopped entirely, but since we know from the U.S. that there’s a common-sense link between these weapons and shootings with a large number of victims, it isn’t much of a stretch.

So does this mean that banning assault weapons would reduce the frequency or number of mass shootings in the U.S.? Maybe. There are a couple factors that defeat a simple apples-to-apples comparison. One is the aforementioned massive difference in the countries’ murder rates — they are just very, very different places when it comes to shootings, so it isn’t necessarily the case that you can translate these findings to the United States. Along those same lines, the sheer number of guns in the U.S. could complicate things — one could make the case that a law reducing the number of the deadliest weapons would have less of an impact here, since it would be easier for would-be shooters to simply use handguns instead.

Still: There are some very good empirical reasons to think an assault-weapon ban like Australia’s would reduce the number and severity of mass shootings here, and the U.S. has never actually tried it. This is something a lot of people fail to realize, and which Webster explains in his article: “the [U.S.] law was written in a way that made it possible for gun manufacturers to perform slight modifications to make military-style weapons legal for sale. Importantly, the US law did not follow Australia’s NFA model and ban the possession of assault weapons or LCMs and recover the weapons purchased before the ban.” So there were still a ton of those weapons floating around, and the bill only lasted from 1994 to 2004, anyway. “The point is that we’ve never made a good faith effort,” said Shapiro. “We will not go to the lengths that Australia did for a variety of reasons, but it demonstrates that access to semi-automatic long guns that accept large-capacity ammunition magazines matters for mass shootings.”

As you can probably tell, measuring all this stuff is complicated. What we do know is that Australia passed a strict gun-control law that outlawed the mostly deadly weapons, and that nation hasn’t had a mass shooting since. In the U.S., we’ve never tried that, and mass shootings — frequently involving weapons that are illegal in Australia — have become a horrifying, relentless part of our news cycle. Make of that what you will.