MYTH: Right-to-Carry Laws Prevent Mass Shootings and Reduce Crime

Summary:

• Research John Lott claims that right-to-carry laws, which encourage the concealed carry of firearms, reduce crime and prevent mass shootings. 
• Lott’s findings on mass shootings are not supported by other academics, including Carlisle Moody, who has concurred with him on concealed carry laws in the past.
• The evidence suggests that right-to-carry laws are associated with more mass shootings and gun deaths.

Lott’s Claim:

Over the last 30 years, many US states have lowered the requirements to carry a firearm in public by passing right-to-carry (RTC) laws. States that have RTC laws either do not require a permit to carry a concealed firearm or issue concealed carry permits on a “shall issue” basis, meaning authorities have little to no discretion to deny a permit. 

In his 2003 book The Bias Against Guns, John Lott argues that right-to-carry laws deter public mass shooters more than other murderers and criminals because mass shooters are concerned about being stopped by an armed civilian. He explicitly states: “Right-to-carry laws reduce the number of people killed or wounded from multiple victim public shootings. Many attackers are completely deterred from attacking.”

Lott’s own analysis found that RTC laws were associated with significant reductions in the number of public mass shootings and in the total number of casualties from public mass shootings. Lott’s study covers 1977 to 1997 and excludes certain types of incidents like  shootings connected to other crimes such as robbery, drugs, and gangs. He excludes these incidents because Lott argues one can reasonably expect that  people committing crimes will carry guns. Lott concludes that the passage of a RTC law “is the only gun law that appears to have any real impact” on public mass shootings.

The Facts: 

Lott’s analysis is based on a flawed model and is contradicted by many other studies. 

In a summary of the evidence on the effects of concealed carry on mass shootings, RAND, an American nonprofit global think tank, said Lott’s regression “models had an unfavorable ratio of estimated parameters to observations (approximately one to eight), suggesting that the model may have been overfit, and thus the estimated effects of these laws may be poor indicators of their true effects. In addition, the model did not adjust for clustered standard errors. Together, these shortcomings suggest that the model results may not accurately describe the true effects of shall-issue laws.” (Emphasis added.)

Of the five studies examining concealed carry laws and mass shootings identified by RAND, only the Lott study found that shall-issue laws led to fewer mass shootings and casualties. For example, a 2002 study by Grant Duwe, Tomislav Kovandzic, and Carlisle Moody examined RTC laws from 1977 to 1999 found “virtually no support for the hypothesis that the laws increase or reduce the number of mass public shootings.” This is especially noteworthy since Moody is a frequent collaborator of Lott and generally agrees with Lott on other concealed carry issues.

Recent studies by Reeping, et al and Doucette, Crifasi, and Frattaroli have found that right-to-carry laws are associated with more gun violence including mass shootings, but are not an apples-to-apples comparison because the recent studies do not have the same focus as Lott’s study. A 2019 study by Paul Reeping et al. found that a 10 unit increase in state gun law permissiveness, which includes RTC laws, was associated with a 11.5% higher rate of mass shootings. Another 2019 study by Mitchell Doucette, Cassandra Crifasi, and Shannon Frattaroli found that passing a RTC law between 1992 and 2017 was associated with a 24% increase in firearm workplace homicide rates. 

Sources:

John Lott, The Bias Against Guns: Why Almost Everything You’ve Heard About Gun Control Is Wrong, 2003
Grant Duwe, Tomislav Kovandzic, and Carlisle E. Moody, “The Impact of Right-to-Carry Concealed Firearm Laws on Mass Public Shootings,” Homicide Studies, 2002
Samantha Cherney, “Effects of Concealed-Carry Laws on Mass Shootings,” RAND, April 22, 2020
Michael Luca, Deepak Malhotra, and Christopher Poliquin, “The Impact of Mass Shootings on Gun Policy, working paper,” Harvard Business School, 2016
Mark Gius, “The Effects of State and Federal Gun Control Laws on School Shootings,” Applied Economics Letters, 2018
Paul M Reeping, Magdalena Cerdá, Bindu Kalesan, Douglas J Wiebe, Sandro Galea, Charles C Branas, “State gun laws, gun ownership, and mass shootings in the US: cross sectional time series,” BMJ, March 2019
Mitchell L. Doucette, Cassandra K. Crifasi, and Shannon Frattaroli, “Right-to-Carry Laws and Firearm Workplace Homicides: A Longitudinal Analysis (1992–2017),” American Journal of Public Health, December 2019