Summary: Australia’s 1996 National Firearms Agreement (NFA) banned several types of firearms and resulted in the government buying hundreds of thousands of the banned weapons from their owners. Studies examining the effect of removing so many weapons from the community have found that homicides, suicides, and mass shootings were less common after the NFA was implemented. There is more evidence consistent with the claim that the NFA caused reductions in firearm suicides and mass shootings than reductions in violent crime generally, but there is also evidence that raises questions about whether those changes can be attributed to the NFA or to other factors that influenced suicide and mass shooting rates around the time the NFA was implemented.

Following a 1996 mass shooting in which 35 people in Tasmania, Australia, were killed, Australian states and territories reached the National Firearms Agreement (NFA) to adopt “a consistent set of firearm management principles into their own legislation and regulation” (McPhedran, 2016, p. 65). The principle features of the agreement, as described in a study on regulatory reform, were as follows:

Ban on importation, ownership, sale, resale, transfer, possession, manufacture, or use of all self loading centre rifles, all self loading and pump action shotguns, and all self-loading rimfire rifles (some exemptions allowable to primary producers and clay target shooters)

Compensatory buyback scheme through which firearm owners would be paid the market value for prohibited firearms handed in during a 12-month amnesty

Registration of all firearms as part of integrated shooter licensing scheme

Shooter licensing based on requirement to prove “genuine reason” for owning a firearm, including occupational use, demonstrated membership of an authorized target shooting club, or hunting (with proof of permission from a rural landowner)

Licensing scheme based on five categories of firearms, minimum age of 18 years, and criteria for a “fit and proper person”

New licence applicant required to undertake accredited training course in firearm safety

As well as licence to own a firearm, separate permit required for each purchase of a firearm subject to a 28-day waiting period

Uniform and strict firearm storage requirements

Firearms sales to be conducted only through licensed firearm dealers and all records of sale to be provided to the police

Sale of ammunition only for firearms for which purchaser is licensed and limitations on quantities purchased within time period. (Ozanne-Smith et al., 2004, pp. 282–283)

During the 12-month amnesty (the second principle in the list), Australia purchased back 695,940 newly prohibited firearms as of August 2001, and during a second buyback, in 2003, 68,727 handguns were destroyed (Chapman, Alpers, and Jones, 2016).[1]

The 2004 National Research Council (NRC) review of gun policies did not comment extensively on the Australian reform. The report referenced a 2003 study (Reuter and Mouzos, 2003) that estimated that approximately 20 percent of Australia’s firearms were retrieved during the buyback but that these weapons did not account for a significant share of the prior homicides or violent crimes. Whereas Reuter and Mouzos (2003) found no evidence of a decline in homicides, violent crime, or total suicides after the buyback, they noted that, during the six post-law years, there “were no mass murders with firearms and fewer mass murders than in the previous period,” findings that NRC (2004) called “weak tests given the small numbers of such incidents annually.”

Methods

In our review, the available evidence of the effect of the NFA on mass shootings, homicides, and suicides all derives from the same preliminary source. McPhedran (2016) reviewed the effect of the NFA on homicide. Studies that were included had to meet the following criteria:

Contain original quantitative data analysis (i.e., the author excluded summaries, representations, or replications of previously published work; letters to the editor; opinion pieces; literature reviews; legal analyses; media analyses; and the like).

Focus specifically on firearm homicide in Australia.

Include time-series data.

Use formal statistical methods to detect legislative impacts or change over time.

Although McPhedran’s review was limited to homicide, the five studies that were included in the review also examined suicide. Thus, we use the same five articles to examine these outcomes.

We also include additional studies for mass shootings and suicide identified in our search for U.S. policy effects. Two studies—­Chapman, Alpers, and Jones (2016) and Baker and McPhedran (2015)—are also relevant to homicide but were published the same year as or shortly before McPhedran (2016) and thus were not included in her review but are referenced here.

Because NFA principles were applied universally throughout Australia, researchers are generally unable to conduct case-control analyses, such as comparing outcomes in one Australian state that enacted a law with outcomes in another state that did not (McPhedran, 2016; Chapman et al., 2006). As a result, most researchers exploited changes over time to assess the effects of the law, although one examined changes in mass shootings in Australia versus New Zealand (McPhedran and Baker, 2011) and two examined regional variation: Ozanne-Smith et al. (2004) examined one Australian state (Victoria), which had firearm legislation in place prior to the NFA, relative to the rest of Australia, and Leigh and Neill (2010) examined variation in the number of guns in each state that were reportedly “bought back” and the association with suicide and homicide rates in those states.

Suicide

McPhedran (2016) produced an evidence table, and we created a modified version of it that focuses on suicide (see table below). Six of the studies found statistically significant evidence that suicide rates declined more rapidly after implementation of the NFA in 1996 than before. In addition, Leigh and Neill (2010) found that Australian states with the highest per capita rates of turning in banned guns also had greater declines in firearm suicides. These findings are consistent with the claim that the NFA reduced suicides in Australia (Baker and McPhedran, 2007; Baker and McPhedran, 2015; Chapman, Alpers, and Jones, 2016; Chapman et al., 2006; Klieve, Sveticic, and De Leo, 2009; Ozanne-Smith et al., 2004).

Two sets of findings, however, raise questions about whether these observed associations are attributable to a causal effect of the NFA. First, two models (­McPhedran and Baker, 2012; Lee and Suardi, 2010) that used similar methods examined changes in suicide rates over time and failed to find evidence of a break at the time of the NFA, with one exception: McPhedran and Baker (2012) examined trends in population subgroups and found some evidence of a break in 1997 in firearm suicide trends among those aged 35–44, but the evidence was not robust across statistical tests.

Perhaps more importantly, three studies that did find reductions in firearm suicides also found statistically significant reductions in nonfirearm suicides (­Chapman et al., 2006; Chapman, Alpers, and Jones, 2016; Baker and McPhedran, 2015). McPhedran and Baker (2012) also found significant breaks in the time series of hanging suicides in 1997 among those aged 15–24 and 25–34, and in 1998 among those aged 35–44. Although it is possible that the NFA caused reductions in firearm and nonfirearm suicides, the mechanism by which it may have had an effect on nonfirearm suicides was not obvious, nor would most public health experts predict such an effect. An alternative explanation for these findings is that factors other than the NFA led to changes in nonfirearm suicide rates around 1996, and these factors might also have had an effect on firearm suicide that was independent of the NFA’s effects. Another study found only nonsignificant declines in nonfirearm suicide rates after passage of the NFA, despite finding significant decreases in firearm suicides associated with the number of banned guns turned in across Australia’s provinces and states (Leigh and Neill, 2010). The study did not show, however, that the declines in firearm suicide rates associated with turning in guns were significantly greater than the nonsignificant declines in nonfirearm suicides. Thus, although there is some evidence that the 1996 agreement reduced firearm suicides in Australia, studies also found significant reductions in nonfirearm suicides at the same time, calling into question whether it was the NFA or some other concurrent events that led to reductions in gun and nongun suicides.

Summary of Studies Examining the Effects of the National Firearms Agreement on Suicide in Australia Study Details Available Statistical Information and Main Findings Ozanne-Smith et al., 2004 Geographic Coverage Focus on one Australian state (Victoria); comparisons performed against the rest of Australia Statistical Method Poisson regression Research Focus Did trends differ between the different periods? Period 1979–2000 Firearm Suicide −31.7-percent change (a reduction) between 1979–1987 and 1988–1996 (p = 0.008) No statistical information provided for 1988–1996 and 1997–2000 or for 1979–1987 and 1997–2000 Nonfirearm Suicide Not available Total Suicide Not available Chapman et al., 2006 Geographic Coverage Whole of Australia Statistical Method Negative binomial regression Research Focus Did trends differ before and after 1997? Period 1979–2003 Firearm Suicide Trend before 1997: IRR = 0.970 (95% CI: 0.964, 0.977) Trend after 1997: IRR = 0.926 (95% CI: 0.892, 0.961) Ratio of slopes: IRR = 0.954 (95% CI: 0.922, 0.987); p = 0.007 (sig.) Nonfirearm Suicide Trend before 1997: IRR = 1.023 (95% CI: 1.018, 1.029) Trend after 1997: IRR = 0.959 (95% CI: 0.951, 0.968) Ratio of slopes: IRR = 0.938 (95% CI: 0.920, 0.956); p < 0.001 (sig.) Total Suicide Trend before 1997: IRR = 1.010 (95% CI: 1.005, 1.015) Trend after 1997: IRR = 0.956 (95% CI: 0.948, 0.964) Ratio of slopes: IRR = 0.946 (95% CI: 0.930, 0.963); p < 0.001 (sig.) Baker and McPhedran, 2007 Geographic Coverage Whole of Australia Statistical Method Autoregressive integrated moving average (ARIMA), paired sample t-tests Research Focus Did trends differ before and after 1996? Period 1979–2004 Firearm Suicide Mean predicted rate (per 100,000) after 1996: 1.85

Mean observed rate (per 100,000) after 1996: 1.22 p < 0.001 (sig.) Nonfirearm Suicide Mean predicted rate (per 100,000) after 1996: 11.82

Mean observed rate (per 100,000) after 1996: 11.31 p = 0.21 (n.s.) Total Suicide Not available Klieve, Sveticic, and De Leo, 2009 Geographic Coverage Queensland Statistical Method Negative binomial regression Research Focus Did trends differ before and after 1996? Period 1988–2004 Firearm Suicide Queensland ratio of trends (1990–2004): 1.0072; p = 0.7794 (n.s.) Australia ratio of trends: 0.9672; p = 0.0102 (sig.) Nonfirearm Suicide Not available Total Suicide Not available Lee and Suardi, 2010 Geographic Coverage Whole of Australia Statistical Method ARIMA, Quandt (Chow), Bai and Perron Research Focus Were there changes in the time-series structure? Period 1915–2004 Firearm Suicide Quandt: no sig. break Bai and Perron: UDmax = 10.45; critical value = 8.88 (p < 0.05)

WDmax = 10.68; critical value = 9.91 (p < 0.05) * Estimated break date: 1987 (90% CI: 1978, 2001) Nonfirearm Suicide Quandt: no sig. break Bai and Perron: UDmax = 3.97; critical value = 8.88 (n.s.)

WDmax = 4.72; critical value = 9.91 (n.s.) Total Suicide Not available Leigh and Neill, 2010 Geographic Coverage Whole of Australia, based on jurisdiction-level data Statistical Method Linear regression Difference between averages for 1990–1995 and 1998–2003 Research Focus What was the estimated effect of the number of guns handed in on firearm, nonfirearm, and total suicides? Period 1990–2003 Firearm Suicide 1990–1995 average death rate (per million) = 2.55 Implied change in death rate 1998–2003 (per million) = −1.9 (95% CI: −2.9, −0.8); p = 0.004 (sig.) Nonfirearm Suicide 1990–1995 average death rate (per million) = 10.2 Implied change in death rate 1998–2003 (per million) = 1.7 (95% CI: −4.7, 8.2); p = 0.532 (n.s.) Total Suicide 1990–1995 average death rate (per million) = 12.7 Implied change in death rate 1998–2003 (per million) = −0.01 (95% CI: −6.2, 5.9); p = 0.956 (n.s.) McPhedran and Baker, 2012 Geographic Coverage Whole of Australia Statistical Method Zivot-Andrews, Quandt Research Focus Were there changes in the time-series structure? Period 1907–2007 Firearm Suicide Zivot-Andrews: Estimated break date, ages 25–34:

1994 (intercept only, 1979–2007; p < 0.05)



1994 (intercept and trend, 1979–2007; p < 0.05)



Estimated break date, ages 35–44:

1993 (intercept only, 1979–2007; p < 0.05)



1997 (intercept and trend, 1979–2007; p < 0.05) Quandt: Estimated break date 1997, ages 35–44 (1979–2007): Max F statistic = 3.90 (n.s.) Nonfirearm Suicide Results for suicide by hanging: Zivot-Andrews: Estimated break date, ages 15–24:

1987 (intercept only, 1907–2007; p < 0.05)



1997 (intercept and trend, 1979–2007; p < 0.10)

Estimated break date, ages 25–34: 1998 (intercept and trend, 1979–2007; p < 0.01)

Estimated break date, ages 35–44: 1998 (intercept and trend, 1979–2007; p < 0.05) Quandt: Estimated break date 1987, ages 15–24 (1979–2007): Max F statistic = 176.38; p < 0.01

Estimated break date 1987, ages 15–24 (1979–2007): Max F statistic = 63.20; p < 0.01

Estimated break date 1987, ages 25–34 (1979–2007): Max F statistic = 54.90; p < 0.01

Estimated break date 1988, ages 25–34 (1979–2007): Max F statistic = 14.20; p < 0.01 Total Suicide Not available Baker and McPhedran, 2015 Geographic Coverage Whole of Australia Statistical Method ARIMA Research Focus Did trends differ before and after 1996? Period 1979–2010 Firearm Suicide Mean predicted rate (per 100,000) after 1996: 1.50

Mean observed rate (per 100,000) after 1996: 1.05 p < 0.001 (sig.) Nonfirearm Suicide Mean predicted rate (per 100,000) after 1996: 12.35

Mean observed rate (per 100,000) after 1996: 10.64 p < 0.0.1 (sig.) Total Suicide Not available Chapman, Alpers, and Jones, 2016 Geographic Coverage Whole of Australia Statistical Method Negative binomial regression Research Focus Did trends differ before and after 1996? Period 1979–2013 Firearm Suicide Ratio of trends = 0.981 (95% CI: 0.970, 0.993); p = 0.001 (sig.) Step change = 0.652 (95% CI: 0.582, 0.731); p < 0.001 (sig.) Nonfirearm Suicide Ratio of trends = 0.981 (95% CI: 0.958, 0.973); p < 0.001 (sig.) Step change = 1.070 (95% CI: 0.988, 1.159); p = 0.10 (n.s.) Total Suicide Ratio of trends = 0.975 (95% CI: 0.968, 0.982); p < 0.001 (sig.) Step change = 1.004 (95% CI: 0.931, 1.083); p = 0.90 (n.s.) NOTE: CI = confidence interval; IRR = incidence rate ratio; sig. = significant; n.s. = not significant. * UDmax and WDmax are test statistics evaluating whether there is evidence that time-series data show a departure from their expected trendline.

Violent Crime

Australia’s homicide rate was decreasing prior to the 1996 NFA. Thus, as reviewed by McPhedran (2016), the research focus has largely investigated whether the rate at which homicides were declining changed after the NFA was implemented (Baker and McPhedran, 2007; Chapman et al., 2006; Ozanne-Smith et al., 2004; Baker and McPhedran, 2015; Chapman, Alpers, and Jones, 2016). Other lines of research have examined the relationship between the number of firearms turned in during the buyback period and firearm homicides (Leigh and Neill, 2010) and for any structural breaks in the rate of firearm homicides between 1915 and 2004 (Lee and Suardi, 2010). No study found statistically significant evidence that trends in firearm homicides changed from before to after implementation of the NFA.[2] However, Chapman, Alpers, and Jones (2016) found that the ratio of pre-law to post-law trends was statistically significant and less than one (suggesting a more rapid decline in the post-law period) for total homicide, nonfirearm homicide, and total firearm deaths (suicide and homicide). The greater declines in nonfirearm homicides led the authors to doubt whether any changes can be attributed to the NFA.

Mass Shootings

Two studies examined the impact of the NFA on mass shootings. Both studies indicated that there were mass shootings in Australia prior to enactment of the law, but there were none thereafter. Specifically, Chapman, Alpers, and Jones (2016)—which defined mass shootings as those in which five or more people, excluding the shooter, were killed by gunshot—found that there were 13 mass shooting incidents in Australia between 1979 and the NFA’s implementation in 1996 but none between 1997 and May 2016. Using the broader definition of four or more people killed, McPhedran and Baker (2011) reported that there were 12 such incidents from 1980 to 1996 and none between 1997 and 2009. McPhedran and Baker (2011) also reported that there have been no mass shootings in New Zealand since 1997 (though three between 1980 and 1996 and one in February 1997 while the gun buyback provisions of the NFA were being implemented in Australia), even though New Zealand did not introduce a similar ban on certain firearms. On the basis of this analysis, the authors suggest that reductions in mass shootings in Australia are not likely to be attributable to the NFA, because similar reductions were seen elsewhere without laws like the NFA. However, New Zealand did pass a law in 1992 (though not subsequently) tightening its regulation of guns. In other words, mass shootings in New Zealand declined from four in the years prior to and during implementation of the NFA in Australia to zero thereafter, and that reduction occurred shortly after imposing stricter gun legislation in New Zealand. Therefore, we do not view the McPhedran and Baker (2011) results as offering a strong refutation of the possibility that the NFA caused a reduction in mass shootings in Australia.

Conclusion

Analyses of the effects of Australia’s NFA are limited by the lack of a comparison group—the exceptions being Leigh and Neill (2010) and McPhedran and Baker (2011). Attributing reductions in suicide and homicide rates to the NFA is complicated by the fact that these rates were decreasing even before the NFA was enacted. There is more evidence consistent with the claim that the NFA caused reductions in firearm suicides and mass shootings than reductions in violent crime, but there is also evidence that raises questions about whether those changes can be attributed to the NFA or to other factors that influenced suicide and mass shooting rates around the time the NFA was implemented.

Updated August 21, 2018, to correct minor errata in the "Mass Shootings" section.