What the data actually say about assault weapons

President Biden wants to ban assault weapons with high-capacity magazines. Illinois House Democrats have put forward a state-wide ban on such weapons. Several mass murders, including the one earlier this year at the Robb Elementary School in Uvalde, Texas and the recent Colorado Springs nightclub shooting involved the assailant using an assault weapon to inflict harm on innocent people. All such deaths are senseless, needless and avoidable. 

Yet, in a diverse and complex nation like the United States, personal and population risks are ubiquitous. Individuals seek to reduce their personal risk, while governments are best positioned to enact laws and policies that reduce population risk. That is why people make lifestyle and dietary choices that influence their personal wellbeing, while government policies can impact access to care that influences population wellbeing.

In 2020, almost 3.4 million people died in the United States, with heart disease, cancer and COVID-19 the top three causes. 

Where do firearm deaths fall in the mix?

They accounted for just over 45,000 of all deaths, with more suicides (54 percent) than homicides (43 percent). The overall 2021 numbers are similar, with the 2022 numbers on track to have comparable counts.

Mass murders, defined as four or more people killed, not including the shooter, accounted for 113 deaths in 2020 and 177 in 2021. Mass killings, defined as four or more people killed or injured, also not including the shooter, accounted for 513 deaths in 2020 and 705 deaths in 2021. 

To put all such numbers into perspective, other avoidable deaths include automobile accident fatalities (almost 39,000 in 2020 and estimated to be around 43,000 in 2021) and drug overdoses (over 93,000 in 2020 and over 107,000 in 2021). 

Given that suicides are associated with the majority of firearm deaths, and handguns a common weapon used, would banning handguns be an effective way to reduce suicide deaths? It would likely have prevented many of them, given that access to firearms is a risk factor for suicide. Yet, such a blanket ban is impractical and unrealistic to implement any time soon. 

There is also no indication that assault weapons are involved in single person suicides.

Based on the data, what are the benefits of an assault weapon ban?

The assault weapon threat is actually the potential to inflict massive harm over a short time period. This means that an assault weapon ban would reduce this potential threat. 

Deaths alone also provide too narrow of a measure of risk. People injured adds to the personal and population risk equation. 

Assuming (incorrectly) that all mass murders involved assault weapons, and assuming that all the associated deaths and injuries could have been avoided, this amounts to around 650 deaths over the past four years (2018-2021), fewer than the number of people who will die with or from COVID-19 over any two days this week.

For mass killings, the numbers jump to just over 2,000 deaths and just over 8,000 injuries, all senseless, all needless, all avoidable. However, the preponderance of such events were not executed with assault weapons, although the ones that were had more casualties and were more widely reported in the media. Moreover, with other weapons available, the perpetrators could have resorted to some other means to undertake their attacks (the September mass stabbing in Canada illustrates this point). 

What this data indicate is that an assault weapon ban carries with it a very small reduction in population risk. The issue up for debate is whether this reduction is sufficient to warrant banning them.

If mass killings with assault weapons were leading to 5,000 deaths and 50,000 injuries per year, or several times the current number, the risk calculus shifts strongly in support of a ban.

Governments implement and enforce guardrails that reduce population risk based on costs that are commensurate with benefits. This is why there are speed limits on public roads, why seat belts are mandatory in automobiles, and why government agencies like the Food and Drug Administration and the Drug Enforcement Administration regulate and oversee prescription drugs.

There are clear benefits associated with automobile transportation and pharmaceuticals, while the benefit of or need for assault weapons is more opaque, pushing down the bar for population risk reduction. When children’s lives are at risk, the bar moves down even further. 

What remains open to debate is whether the bar is sufficiently low to warrant government intervention. A consistent conclusion drawn from studies, including those conducted by the government, following the 1994 assault weapons ban is that the data was inconclusive.

What continues to be indisputable is that our nation needs constructive, ideologically-free dialogues on reducing gun violence. Leadership from the judicial, law enforcement and medical communities are key players that must contribute to this discussion. Politician have demonstrated their impotence to make any positive headway on the issue. 

Banning assault weapons may be a good idea for their potential to inflict harm. Such a ban may also have other societal benefits that would justify it. However, arguing for a ban based solely on existing population risk reduction benefits extracted from the data appears to be more about political posturing than data-driven evidence-based analysis. 

Sheldon H. Jacobson, Ph.D., is a professor in Computer Science and the Carle Illinois College of Medicine at the University of Illinois Urbana-Champaign. A data scientist, he applies his expertise in data-driven risk-based decision-making to evaluate and inform public policy.