Policy Evaluation

We analyzed the effect on homicide of changes in state-level gun carrying laws using pooled cross-sectional time-series data for 50 states from 1979-1998.  There was no statistically significant association between changes in concealed carry laws and state homicide rates.  The finding was consistent across a variety of models.

Hepburn, Lisa; Miller, Matthew; Azrael, Deborah; Hemenway, David.  The effect of nondiscretionary concealed weapon carrying laws on homicide.  Journal of Trauma.  2004; 56:676-681.

We analyzed the effect on unintentional firearm fatalities to children of child access prevention (CAP) laws, which allow a firearm owner to be charged with a crime if a child gains access to an unsecured firearm, using pooled cross-sectional time series data for 50 states from 1979 to 2000. We found that states that enacted CAP laws – with felony rather than misdemeanor penalties – experienced grater subsequent declines in the rate of unintentional firearm deaths for children age 0 to 14 years, compared to states not enacting CAP laws.

Hepburn, Lisa; Azrael, Deborah; Miller, Matthew; Hemenway, David.  The effect of child access prevention laws on unintentional child firearm fatalities, 1979-2000.  Journal of Trauma.  2006; 61:423-28.

This article on statistics describes the limitations of studies that claim no effect of gun shows and no effect of the Australian gun buyback.

Hemenway, David.  How to find nothing.  Journal of Public Health Policy.  2009; 30:260-68.

This paper highlights the serious flaws in a study that found no effect of gun shows on homicide or suicide.

Wintemute, Garen; Hemenway, David; Webster, Daniel; Pierce Glenn; Braga Anthony A.  Gun shows and gun violence: Fatally flawed study.  American Journal of Public Health.  2010;100;1856-60.

One section of this chapter discusses the three aspects of regulation: the rules, monitoring of those rules, and punishments if the rules are not complied with.  The Brady bill is discussed as an example of a law with major deficiencies in all three aspects.

Hemenway, David.  Public policy.  In: Guohua Li and Susan P. Baker, eds. Injury Research: Theories, Methods and Approaches. New York: Springer, 2012.

We conducted a state-level ecological study for 2007-2010 and found that states with more firearm laws had lower rates of both gun homicide and gun suicide, even after controlling for race, poverty, unemployment, college education, population density, and non-firearm deaths.

Reviews by the Centers for Disease Control and the Institute of Medicine conclude that the evidence is not strong enough to determine whether or not firearm laws reduce lethal violence.  This study provides evidence consistent with the hypothesis that firearm laws are effective in reducing homicide and suicide.

Fleegler EW, Lee LK, Monuteaux MC, Hemenway D, Mannix R.  Firearm legislation and firearm-related fatalities in the United States.  JAMA-Internal Medicine.  2013; 173:732-40.

An article by Kalesan et al finds that all gun control laws are associated with lower rates associated with higher rates. In a cross-sectional state analysis, universal background checks are most strongly associated with lower firearm mortality. In a Commentary, we discuss some limitations of the article, and that the large effect indicated for individual laws have to be taken with a grain of salt.

Hemenway D. Firearm legislation and mortality in the USA. The Lancet. 2016; 387:1796-97

Our literature review found that, in the US, stronger firearm laws were associated with lower rates of firearm homicide, even after adjusting for demographic and sociologic factors. There was evidence that specific laws such as universal background checks and permit-to-purchase requirements seemed to decrease firearm homicide rates.

Lee LK, Fleegler EW, Farrell C, Avakame E, Srinivasan S, Hemenway D, Monuteaux MC. Firearm laws and firearm homicides: a systematic review. JAMA Internal Medicine. 2017 Jan 1;177(1):106-19.

In a state-level panel study 2006-16, we found that the percentage of guns traced to a dealer within that state was much higher for states with weak gun laws. Four laws independently associated with a lower percentage of in-state guns were permits of firearm purchase, a waiting period, prohibition of firearm possession by persons with a violent misdemeanor conviction, and a requirement to relinquish firearms when a person becomes disqualified.

Collins T, Greenberg R, Siegel M, Xuan Z, Rothman EF, Cronin SW, Hemenway D. State firearm laws and interstate transfer of guns in the United States, 2006-16. Journal of Urban Health. 2018; 95:322-336.

From 1990-2017, there were 69 mass shootings in which at least 6 people were killed. When the perpetrator had a large capacity magazine (LCM), on average there were 62% more deaths. The incidence of these high-fatality mass was more than double the rate in states that did not ban LCMs, and the number of deaths per population was three times higher.

Klarevas L, Conner A, Hemenway D. The effect of large capacity magazine bans on high-fatality mass shootings, 1990-2017. American Journal of Public Health. 2019; 109:1754-1761.

We examined state-level data from 1991-2016. Universal background check laws and permit requirement laws were associated with lower homicide rates among both Black and White populations, and “shall issue” laws were associated with higher homicide rates. Laws that prohibit firearm purchase for violent misdemeanor convictions and require firearm relinquishment for having a domestic violence restraining order were associated with lower Black homicide but not lower White homicide.

Knopov A, Xuan Z, Rothman E, Siegel M, Hemenway D. Impact of state firearm laws on homicide rates among Black and White population in the US, 1991-2016. Health and Social Work. 2019; 44:232-240.

We examined state-level data from 1991-2016. Universal background check laws and may issue laws (police discretion) concerning concealed carry, were associated with lower rates of firearm homicide in large cities but not suburban and rural areas. By contrast, laws that prohibited firearm purchase by individuals convicted of a violent misdemeanor were associated with lower rates of firearm homicide in suburban and rural areas, but not in big cities. Permit requirement laws were associated with lower rates of firearm suicide in all areas.

Siegel M, Solomon B, Knopov A, Rothman E, Cronin S, Xuan Z. Hemenway D. The impact of state firearm laws on homicide rates in suburban and rural areas compared to large cities in the United States, 1991-2016. Journal of Rural Health. 2020: 36:255-265.

We examined the large-scale program in Detriot that demolished over 10,000 vacant buildings in its first 3 years. The program was associated with a 11% reduction in firearm assaults relative to control locations. No effects were observed for illegal drug violations, and no evidence of spatial crime displacement was detected.

Jay J, Miratrix LW, Branas CC, Zimmerman MA, Hemenway D. urban building demolitions, firearm violence, and drug crime. Journal of Behavioral Medicine. 2019; 42:SI626-634.

We examined state homicide and suicide rates 1991-2016 and their relationship with 10 state laws.

Siegel M, Pahn M, Xuan Z, Fleegler E, Hemenway D. The impact of state firearm laws on homicide and suicide deaths in the United States: a cross sectional analysis. Journal of General Internal Medicine. 2019; 34:2021-2028.

This Editorial emphasizes that while reducing access to lethal means reduces suicide, the age limit on gun purchases may not have a large effect on youth suicide since many youth will still have access to household guns.

John A, Azrael D, Miller M. Access to firearms and adolescent suicide. British Medical Journal 2020; 370:m2829.

We evaluated a counseling intervention at four hospital sites in Colorado to improve firearm storage in families with youth aged 10-17 who made ED visits for a behavioral health concern. More families reported improving their firearm storage after the intervention compared to the control group.

Miller M, Salhi C, Barber C, Azrael D, Beatriz E, Berrigan J, Brandspigel S, Betz ME, Runyan C. Changes in firearm and medication storage practices in homes of youth at risk for suicide: Results of the SAFETY study, a cluster emergency department-based, multisite stepped-wedge trail. Annals of Emergency Medicine. 2020; 76:194-205.

In 1991, California passed a comprehensive background check law. In 2018, an internet survey of a representative sample of California adults asked about their most recent firearm acquisition. 45% of those who acquired a gun before 1991 did not have a background check compared to 17% whose most recent purchase came after 1991. Among current California residents who obtained their most recent gun outside of California, 27% did not have a background check. While the California law seems to have an effect, there appear to be gaps in implementation and enforcement.

Kravitz-Wirtz N. Pallin R, Kagawa RMC, Miller M, Azrael D, Wintemute GJ. Firearm purchases without background checks in California. Preventive Medicine. 2021; 145:106414.

Our 2019 national firearms survey showed that many gun owners don’t know their own state’s gun laws. For example, among gun owners in states which had these laws, only 34% of gun owners knew there was a Child Access Prevention Law, only 40% knew there was an Extreme Risk Protection Law, only 60% knew there was a universal background check law, and 64% knew about the requirement to report lost and stolen guns. Not knowing a law exists makes it less likely that gun owners will be influenced by the law.

Rowhani-Rahbar A, Haviland MJ, Azrael D, Miller M. Knowledge of state gun laws among US adults in gun-owning households. JAMA Network Open. 2021; 4:e2135141.

Using data from our 2019 National Firearm Survey, we found that gun owners with children in CAP law states were no more likely to lock their firearms (and most didn’t know whether they lived in a state with a CAP law).

Miller M, Zhang W, Rowhani-Rahbar A. Azrael D. Child access prevention laws and firearm storage: results from a national survey. American Journal of Preventive Medicine. 2022; 62:333-340.

Using data from our 2019 National Firearm Survey, we asked about respondents most recent gun acquisition. For those residing in states with comprehensive background check laws, 12% did not undergo a check, compared to 24% in states without comprehensive background check laws. The differences were largely due to differences in checks during private sales from family/friends/acquaintances, and non-purchase transfers. Comprehensive background checks seem to reduce non-check acquisitions.

Hepburn L, Azrael D, Miller M. Firearm background checks in states with and without background check laws. American Journal of Preventive Medicine. 2022; 62:227-233

This paper models the projected impact of three 2022 Supreme Court decisions including the Bruen case. The model projects over 150 additional firearm deaths and more than 350 additional nonfatal injuries annually from Bruen. These are conservative estimates.

Gaffney A, Himmelstein DU, Dickman S, Myers C, Hemenway D, McCormick D, Woolhandler S. Projected health impacts of three 2022 Supreme Court decisions on COVID-19 workplace protections, handgun carry restrictions, and abortion rights. JAMA Network Open. 2023; 6:e2315578.

This paper provides many examples of using negative control analyses. For example, for Child Access Prevention laws to work, gun owners should probably know that they exist, and change their storage behavior. The effect of these laws should be greater for youth suicide than for suicide by the gun owner. Falsification tests can help indicate causality.

Swanson SA, Miller M. Toward a clearer understanding of what works to reduce gun violence: the role of falsification strategies. American Journal of Epidemiology. 2024; 193:1061-65.

A scoping review of empirical firearm policy research indexed in PubMed 2000-2021 found 124 articles examining any of 18 prespecified firearm policies. One third used legislative score as the primary exposure, and 38% did not examine changes in policy over time. Many assumptions of casual identification were not acknowledged. Only 1/3 included bias analyses.

Rencken CA, Schleimer JP, Miller M, Swanson SA, Rowhani-Rahbar A. Reporting and description of research methodology in studies estimating effects of firearm policies. Epidemiology. 2024; 35:458-468.

Assuming the efficacy of the ERPO law as found in Connecticut, data on over 25 million California adults suggests that, in California, it would take about 22 ERPOs to save one life.

Miller M, Zhang Y, Studdert DM, Sonja Swanson S. Updated estimate of the number of extreme risk protection orders to prevent one suicide. JAMA Network Open. 2024; 7:e2414864.