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SPH Study: Higher Homicide Rates Tied to More Permissive Laws

Examines correlation between concealed-carry laws and homicides


With gun violence, especially mass shootings, dominating the news recently, gun control is in the forefront of issues people are concerned about. A new study led by a School of Public Health researcher has found that less stringent regulations about carrying concealed firearms is associated with significantly higher rates of handgun-related homicide.

The study, funded by the Robert Wood Johnson Foundation, was published online October 19, 2017, in the American Journal of Public Health. It suggests that more permissive concealed-carry laws not only do not promote public safety, but are detrimental to it.

“Some have argued that the more armed citizens there are, the lower the firearm homicide rate will be, because the feared or actual presence of armed citizens may deter violent crime,” says lead author Michael Siegel, an SPH professor of community health sciences. “Our study findings suggest that this is not the case.”

Currently, all states allow certain people to carry a concealed handgun, but there are variations in permitting policy. Nine states have “may issue” laws, giving law enforcement officials wide discretion in issuing concealed carry permits. Police chiefs in these states can deny a permit if they deem the applicant to be at risk for violent behavior, even if there is no criminal history. In the 29 “shall issue” states, there is little or no discretion. And in 12 states, no permit is necessary to carry a concealed handgun.

Using data from the Centers for Disease Control and Prevention’s Web-Based Injury Statistics Query and Reporting Systems database, the researchers mapped out the relationship between changes in state concealed-carry permitting laws over time and total firearm-related homicide rates between 1991 and 2015. They also examined the FBI’s Uniform Crime Reports Supplementary Homicide Reports database to differentiate between handgun and long gun homicides. Previous studies have examined only homicide by all firearms.

The researchers found that “shall issue” laws were associated with a 6.5 percent higher total homicide rate than “may issue” laws, as well as an 8.6 percent higher firearm homicide rate and a 10.6 percent higher handgun homicide rate. The researchers found no impact of shall-issue laws on long gun shootings.

The findings are particularly relevant, the researchers say, because Congress is currently considering national concealed carry reciprocity legislation, which would allow anyone to carry a gun in any state as long as they have a concealed carry permit from the state they live in. The researchers argue that adopting such a policy could lead to significant public health risks.

“The trend toward increasingly permissive concealed carry laws is inconsistent with public opinion, which tends to oppose the carrying of guns in public,” the authors write. “Our findings suggest that these laws may also be inconsistent with the promotion of public safety.”

Other SPH study authors are Ziming Xuan, an associate professor of community health sciences, Craig Ross (SPH’14), a research assistant professor of epidemiology, Sandro Galea, dean and Robert A. Knox Professor, and Bindu Kalesan, an assistant professor of community health sciences and a School of Medicine assistant professor of medicine.

Salma Abdella (SPH’17) can be reached at abdallas@bu.edu.



6 Comments on SPH Study: Higher Homicide Rates Tied to More Permissive Laws

  • John Whalen on 10.23.2017 at 5:52 am

    The researchers are biased and just look for data points to support their biased opinions. In the summertime the days are longer. In the summertime people eat more ice-cream therefore people eat more ice-cream because the days are longer.

    • Beth on 10.24.2017 at 10:28 am

      Hi John,

      I wrote it out in more detail in the post below yours, but the paper was not just biased garbage. If you read the methods, you will find that the researchers spent a lot of time and effort making a model which controls for significant covariates. (see my explanation below).

      You are right the study is not funded by the government, but a private organization. Did you know that the NRA successfully banned all government funds from being used to research the effects of guns on society? Imagine if tobacco companies lobbied to disallow research on the association between smoking and lung cancer? Even if there isn’t an association, why aren’t people allowed to look for it? (what do they have to hide?)

  • Web on 10.23.2017 at 8:34 am

    This is an extremely simplistic study based on the assumption that the method of granting CCW permits (shall vs. may issue) is a causal factor in gun homicide rates. It ignores the population and demographics of the states as well as the percentage of gun ownership. Even more glaring is the omission of any data on whether guns used in homicides were legally obtained or owned, used or provided by a person with a permit. Even if you accept this methodology you might infer that the most permissive states that do not require any permit for concealed carry (“Constitutional carry”) would have the highest incidence of handgun homicides when actually the reverse shows true. Vermont and now NH and Maine all have permitless carry an have among the lowest firearm related homicide rates in the nation. The District of Columbia, where a CCW permit is essentially impossible to obtain (and conveniently left out of the study as not a state) has historically been at the top of this list.

    • Beth on 10.24.2017 at 10:01 am

      Hi Web,

      So if you click the link to the study, you’ll find the following in the abstract:

      “Methods. We compared homicide rates in shall-issue and may-issue states and total, firearm, nonfirearm, handgun, and long-gun homicide rates in all 50 states during the 25-year period of 1991 to 2015. We included year and state fixed effects and numerous state-level factors in the analysis.”

      But what does that actually mean, what actual factors did they control for?

      From the methods of the paper:

      Control variables.
      We controlled for 12 state-level factors that (1) were found in the previous literature to be significantly related to homicide rates and (2) were significantly related to the presence of shall-issue laws in our data set (i.e., the regression coefficient for the variable was significant at a level of P = .05 in a logistic regression with shall-issue law as the dependent variable):household firearm ownership (using the standard proxy, which is the percentage of all suicides committed with a firearm), proportion of Blacks, proportion of young adults aged 18 to 29 years), proportion of men among young adults, proportion of the population living in urban areas, total population, population density, per capita alcohol consumption, the nonhomicide violent crime rate (aggravated assault, robbery, and forcible rape), the poverty rate, unemployment rate, median household income, per capita disposable income, incarceration rate, and per capita number of law enforcement officers.

      Before you assume the study is bad, actually look at the article. People don’t get published if they don’t control for obvious covariates (or even some non-obvious covariates)

  • Will on 10.23.2017 at 9:24 am

    I have to call BS on this left wing liberal study. It doesn’t even mention if the homicides were justifiable. If people are conceal carrying legally and someone attempts to rob, assault, or kill them then they just saved their own lives and the lives of their family by taking some scumbag out instead of being forced to become a victim. I think the national conceal carry law is exactly what is needed. Criminals don’t care about gun laws, they’ll carry a gun regardless of the consequences. Gun laws only restrict lawful citizens who follow laws and force them to be victims by taking away their 2nd amendment rights.

    • Kevin Davidson on 03.04.2018 at 8:51 am

      Justifiable homicides are not a factor. They are less than 3% of all homicides.

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