Study of US mass shootings, firearms homicides suggests two-pronged policy approach
Over the past 30 years, mass shootings have fueled calls for changes in gun ownership and concealed carry legislation, but few studies have evaluated whether permissive gun policies deter mass shootings, and none have determined if their effects are the same on firearms homicides. A new study examined the impact of household gun ownership and concealed carry legislation on annual counts of mass shootings and homicides from firearms in the United States over the last 25 years. The study found that mass shootings occur disproportionately in states with higher levels of gun ownership, while rates of firearms homicides are higher in states with permissive concealed carry policies.
The study, by a researcher at Florida State University (FSU), appears in Justice Quarterly,, a publication of the Academy of Criminal Justice Sciences.
"Policymakers on both sides of the debate over gun control err in assuming that mass shootings are representative of firearms homicides, and that strategies to prevent mass shootings will reduce gun violence," explains Emma Fridel, assistant professor of criminology and criminal justice at FSU, who conducted the study. "Lawmakers must enact legislation focused on helping reduce the thousands of firearms homicides that occur annually in the United States, rather than legislation that responds to the more rare mass shootings, as tragic as they are."
Gun violence is a major public health crisis in the United States, with nearly 40,000 annual deaths from suicide, homicide, and accidents involving firearms. Despite the ubiquity of gun violence, widespread fear of mass shootings has disproportionately influenced public discourse on firearms ownership and legislation. Although household gun ownership has been declining since the early 1990s, gun purchases and applications for permits spike after mass shootings (defined as the killing with a firearm of four or more people in 24 hours).
Mass shootings are also used to garner support for more restrictive or permissive firearms laws. One of the most widely discussed—and most widely implemented—policies to prevent mass shootings is permissive concealed carry legislation, which either does not require an additional permit for a gun owner to carry a concealed weapon or limits law enforcement discretion in issuing permits as long as an applicant meets certain basic requirements. While only 15 states had permissive concealed carry policies in the early 1990s, 41 states had them by 2018.
Despite these changes in gun purchasing and carrying policies, it remains unclear if these measures are an effective deterrent. To address the gap in the literature, Fridel compared the impact of changing household gun ownership and concealed carry legislation on the incidence rate of mass shootings and firearms homicides in all 50 U.S. states. She asked whether levels of household gun ownership and concealed carry legislation affected mass shootings in the same way as they do firearms homicides. Fridel used data on firearms homicides from the Centers for Disease Control and Prevention's Web-Based Injury Statistics Query and Reporting System from 1991 to 2016 and created a unique dataset of 592 mass shootings in the United States during the same period.
She found that that higher levels of gun ownership increase the likelihood of mass shootings. The fact that gun ownership was the only significant predictor of mass shootings suggests that guns are a promising target for intervention.
Fridel found no evidence that permissive concealed carry laws prevent mass shootings or mitigate their damage. And she found that such laws significantly increase the rate of firearms homicides: More permissive concealed carry legislation was associated with an 11% increase in the rate of firearms homicides.
Fridel calls the national trend toward more permissive concealed carry laws "deeply troubling": Since 2007, the number of concealed handgun permits has skyrocketed 273%, not counting those with concealed firearms in permitless carry states. "Permissive concealed carry legislation is a significant contributor to our nation's gun violence epidemic," she says.
Fridel concludes that gun ownership and legislation do not affect mass shootings and firearms homicides in the same way. As a result, she says, policymakers need to enact distinct prevention initiatives to address each type of gun violence. Based on her findings, she suggests that reducing gun ownership (for example, through universal background checks and permit requirements) would benefit efforts to prevent mass shootings, while reinstating more restrictive concealed carry legislation would decrease the overall rate of firearms homicides.
"The fact that neither intervention has a deleterious effect on crime—higher levels of gun ownership do not reduce firearms homicides, and more permissive concealed carry legislation is not associated with a reduction in mass shootings—suggests that a two-pronged approach would be most beneficial in combating mass shootings and firearms homicides," Fridel says.