Prevention of Firearm-Related Injuries with Restrictive Licensing and Concealed Carry Laws

Published 2016
Citation: J Trauma. 81(5):952-960, November 2016


Crandall, Marie MD, MPH; Eastman, Alexander MD; Violano, Pina PhD, MSPH, RN-BC; Greene, Wendy MD; Allen, Steven MD; Block, Ernest MD; Christmas, Ashley Britton MD; Dennis, Andrew DO; Duncan, Thomas DO; Foster, Shannon MD; Goldberg, Stephanie MD; Hirsh, Michael MD; Joseph, D’Andrea MD; Lommel, Karen DO, MHA, MS; Pappas, Peter MD; Shillinglaw, William DO

Author Information

From the University of Florida College of Medicine–Jacksonville, Department of Surgery, Jacksonville, Florida; University of Texas Southwestern Medical Center (A.E.), Department of Surgery, Dallas, Texas; Yale-New Haven Children's Hospital Injury Prevention Center (P.V.), New Haven, Connecticut; Emory University School of Medicine, Department of Surgery (W.G.), Atlanta, Georgia; Penn State Milton S. Hershey Medical Center, Department of Surgery (S.A), Hershey, Pennsylvania; University of Central Florida College of Medicine, Department of Surgery (E.B.), Orlando, Florida; Carolinas Health Care (A.B.C.) Department of Surgery, Charlotte, North Carolina; Cook County Hospital, Department of Trauma (A.D.), Chicago, Illinois; Ventura County Medical Center, Department of Surgery (T.D.), Ventura, California; University of Pennsylvania Reading Health System (S.F.) Department of Surgery, Reading, Pennsylvania; Virginia Commonwealth University (S.G.) Department of Surgery, Richmond, Virginia; University of Massachusetts (M.H.) Department of Surgery, Amherst, Massachusetts; University of Connecticut (D.J.) Department of Surgery, Hartford, Connecticut; University of Kentucky (K.L.) Department of Surgery, Lexington, Kentucky; University of Central Florida College of Medicine (P.P.) Department of Surgery, Orlando, Florida; and Mission Hospitals Asheville (W.S.) Department of Surgery, Asheville, North Carolina.

Submitted: August 8, 2016, Revised: August 14, 2016, Accepted: August 15, 2016, Published online: September 16, 2016.

Presentations: These data were presented at the Eastern Association for the Surgery of Trauma Annual Scientific Assembly in San Antonio, TX, January 2016.

Address for reprints: Marie Crandall, MD, MPH, FACS, University of Florida College of Medicine Jacksonville, 655W. 8th Street, Jacksonville, FL 32209; email:


In the past decade, more than 300,000 people in the United States have died from firearm-related injuries.[1] Our firearm death rate far exceeds that of other high-income countries and outnumbers fatalities from all wars in the history of the United States.[2–4]

Firearm-related injuries are associated with heavy societal costs, both financial and psychosocial. In 2010, medical and work loss–related costs related to firearm injuries were estimated to be approximately US $174.1 billion.[1] Among individuals and communities, exposure to persistent gun violence is associated with negative well-being, societal, and behavioral outcomes including poor cognitive functioning, depression, and posttraumatic stress disorder.[5–7]

Many strategies for gun violence prevention have been proposed or used, both in the United States and around the world. Some include primary prevention efforts to decrease interpersonal violence, such as school safety initiatives, whereas other efforts focus on the lethality or accessibility of the weapons, such as trigger locks. Finally, some strategies focus on legislative actions, such as restrictive licensing of firearms. The latter are some of the most controversial and widely debated policies.

Restrictive licensing prohibits individuals from purchasing or owning firearms for various reasons, such as history of domestic violence or mental health conditions. The theory behind these restrictions is that individuals at high risk to harm themselves or someone else would be prevented from having access to firearms. In practice, state licensing restrictions vary. Common restrictions include those that deny gun licenses to individuals who have been convicted of a felony, those who have been convicted of domestic violence offenses, and individuals with mental health issues.

Concealed carry laws (CCLs) regulate the ability to legally carry a firearm in a concealed manner. Licenses to own a gun are required for this in all states, but states vary in their screening regulations. Some states are considered “unrestricted” and allow anyone who can lawfully own a firearm to carry a concealed weapon. Other states are “shall issue,” such that the state has various restrictions before a separate license will be issued to carry a concealed weapon. The remaining states are “may issue”; where even if restrictive criteria are met, issuance of the license is at the discretion of the state. Advocates for concealed carry permits have argued that these laws make society safer, because people may be less likely to commit crimes if they do not know who might be carrying a firearm.


The objective of this practice management guideline was to evaluate the effect of legislative efforts to curb gun violence in the United States. We were particularly interested in the effect of restrictive licensing and CCLs on the prevention of firearm injuries, and we focused on the United States, because it is the country with the most contentious debate surrounding this topic.

A broad-based committee of surgeons and nurses was formed from the membership of the Eastern Association for the Surgery of Trauma Injury Control and Violence Prevention Section, and the Eastern Association for the Surgery of Trauma Guidelines Section. The team included individuals with a range of research experience and many with military and/or civilian law enforcement backgrounds. We created the Populations, Intervention, Comparator, and Outcome (PICO) questions of interest. All group members felt that any type of firearm injuries, fatal or nonfatal, were critically important to answering the questions.

PICO Questions


Population: All individuals in the U.S.

Intervention: Restrictive gun licensing

Comparator: No restrictive gun licensing

Outcome: Firearm injuries, including nonfatal injuries, homicides, and suicides


Population: All individuals in the United States.

Intervention: Concealed carry laws.

Comparator: No concealed carry laws.

Outcome: Firearm injuries, including nonfatal injuries, homicides, and suicides.


Inclusion Criteria for this Review

Study Types

Studies included randomized controlled trials, prospective and retrospective observational studies, and case-control studies. Case reports, conceptual pieces, and reviews containing no original data or analyses were excluded. We excluded editorials, opinion articles, and studies not addressing the PICO questions. We included all studies published between January 1, 1900, and April 30, 2016. We did not restrict by publication language, but we limited our analysis to studies of the United States population.

Participant Types

We included all relevant studies, irrespective of age, race, sex, or other demographic characteristics.

Intervention Types

We reviewed all studies which evaluated the effects of restrictive licensing and CCLs on the prevention of firearm-related injuries.

Outcome Measure Types

We limited the review to studies in which a firearm injury was the outcome; we included fatal and nonfatal injuries, and included both intentional and unintentional mechanisms.

Review Methods

Search Strategy

Figure 1. MESH search terms. MESH, medical subject heading.

Figure 1. MESH search terms. MESH, medical subject heading.

References were identified by research librarians using the MEDLINE database in the National Library of Medicine; the National Institute of Health was searched using Entrez . Additionally, the following databases were also searched: Embase, Cochrane Central Register of Controlled Trials, PsychINFO, Cumulative Index of Nursing and Allied Health Literature (CINAHL), Science Citation Index, Social Sciences Citation Index, Art and Humanities Citation Index, and Conference Proceedings Citation Index. The initial search was performed in November 2013, then a second search in June 2015, and a final search in April 2016. The search was designed to identify all citations regarding the prevention of firearm-related injuries by restrictive licensing and/or CCLs. In addition to the electronic search, we manually searched the bibliographies of recent reviews and articles. Figure 1 contains the medical subject heading terms used for the literature searches.

Study Selection

Figure 2. PRISMA Flow Diagram.

Figure 2. PRISMA Flow Diagram.

After each literature search, two independent reviewers (M.C., P.V.) screened the titles and abstracts, excluding reviews, case reports, articles in which injury was not the outcome measure, and unrelated articles. The resulting studies were used for the review. The study selection process is displayed in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram for Figure 2.

Data Extraction and Management

All references used for the review were entered into a Microsoft Excel spreadsheet containing information on authors, article title, study methodology, and intervention and outcome measures. A master copy was provided to all reviewers. All articles, grading resources, and instructions were electronically available to all members of the writing team. Each independent reviewer shared his or her PICO sheet and literature review with all members of the team. Independent interpretations of the data were shared through group email, conference calls, and in-person discourse. No major reviewer discrepancies in grading occurred.

Methodologic Quality Assessment

We used the validated Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology for this study.[8 ][9] The GRADE methodology entails the creation of a pre-determined PICO question or set of PICO questions that the literature must answer. A rank order (1–9) is assigned to each outcome in terms of importance. For this particular study, all outcomes were determined to be GRADE rank order 9, or critically important. Each designated reviewer independently evaluated the data in aggregate with respect to the quality of the evidence to adequately answer each PICO question and quantified the strength of any recommendations. Reviewers are asked to determine effect size, risk of bias, inconsistency, indirectness, precision, and publication bias.

Recommendations are based on the overall quality of the evidence. GRADE methodology suggests the phrases, “we recommend” for strong evidence, and “we conditionally recommend” for weaker evidence.


As of 2016, a total of 27 studies were included for analysis. Of the original 4,673 studies identified, 3,623 remained after removing duplicates. Two hundred twenty-five case reports, case series, and reviews were excluded, and 3,379 studies were removed because they did not focus on firearm injury prevention or did not address our comparators of interest. Finally, seven additional studies were identified in two separate, subsequent literature reviews. This left a total of 14 studies which merited inclusion for PICO 1 and 13 studies merited inclusion for PICO 2. All studies were in English, and all were from the United States (Tables 1 and 2).

TABLE 1. Evidence Table for Restrictive Gun Laws and Firearm Injury Prevention

TABLE 1. Evidence Table for Restrictive Gun Laws and Firearm Injury Prevention

TABLE 2. Evidence Table for Concealed Carry Laws and Firearm Injury Prevention

TABLE 2. Evidence Table for Concealed Carry Laws and Firearm Injury Prevention


Should Restrictive Licensing Policies be Used to Prevent Firearm Injuries? (PICO 1)

Of the 14 studies analyzed with regard to PICO 1,[10–23] all were population-based, longitudinal studies of restrictive gun licensing laws; two were performed in major metropolitan areas (Washington, DC[10] and Detroit[11]), one analyzed data from a single state (CT[20]), whereas the rest analyzed data from multiple states. Thirteen of the 14 studies showed reductions in some aspect of firearm-related injuries from 7% to 40%.[10 ][12–23]

Article Summaries for PICO 1

Loftin et al.[10] examined the effect of a law passed in 1976 that effectively banned the purchase, sale or transfer of possession of firearm in Washington, DC. Homicides and suicides in the capital were reviewed from 1968 through 1987. Introduction of this law coincided with a 25% reduction in firearm-related homicide (a decrease of 3.3/month) and a 23% decrease in firearm-related suicide (decrease of 0.6/month). There were no associated increases in homicides or suicides by other means.

In the mid-1980s, Detroit was recognized as the “Murder Capital of The United States” with a crude homicide rate of 59 per 100,000 people, the highest of any large city at the time. In response to this, in late 1986, the Detroit City Council enacted a local ordinance that imposed a mandatory jail sentence on anyone convicted of unlawfully concealing a pistol or carrying a firearm in the city. O'Carroll et al.[11] conducted a set of interrupted time-series analyses to evaluate the impact of the ordinance on the incidence of firearm-related homicides. This study found that homicides actually increased after the law was passed overall, though the fraction that occurred in public decreased slightly. The investigators cited local law enforcement, noting that the laws were “unenforced,” which they felt limited interpretation of these data.

In 1994, the Brady Handgun Violence Prevention Act was introduced and established a nationwide requirement that licensed firearms dealers institute a mandatory waiting period and background check for handgun purchases. Ludwig and Cook[12] examined the effect of Brady Act implementation on homicide and suicide rates in the United States by analyzing vital statistics data from 1985 through 1997 obtained from the National Center for Health Statistics. They compared a “treatment” group, containing 32 states directly affected by the Brady Act with a “control” group that had equivalent legislation in place before the passage of the national act. There were no changes in rates of homicides or suicides between the two groups with the exception of a decrease in firearm suicides in individuals 55 years of age and older (−0.92 per 100,000; 95% confidence interval [CI], −1.43 to −0.42), and the effect was strongest if both a background check and a waiting period were implemented (−1.03 per 100,000; 95% CI, −1.58 to −0.047). Ruddell and Mays[13] used ordinary least squares regression modeling of state data controlled for urbanization, demographics, firearm density, violent crime, and offender density to determine the effects of Brady Act legislation. They found a consistent inverse correlation between firearm homicide rates and background check stringency. Similarly, Rodríguez Andrés and Hempstead[18] found an association between restrictive firearm licensing and male suicides, but not all provisions affected all men the same; for example, prohibitions on minors purchasing firearms affected younger men, and waiting periods affected older men.

Sen and Panjamapirom[19] examined data obtained from the United States Bureau of Justice Statistics Surveys of State Procedures Related to Firearm Sales and the US Centers for Disease Control's Web-based Injury Statistics Query and Reporting System to conduct a cross-sectional time series analysis from 1996 to 2005. Like previous studies mentioned, their goal was to examine the relationship between the types of background check information required by states before firearm purchases and firearm homicide and suicide deaths. Using negative binomial models, the authors found that more background checks are associated with fewer homicide (Incidence Rate Ratio [IRR], 0.93; 95% C, 0.91–0.96) and suicide (IRR, 0.98; 95% CI, 0.96–1.00) deaths. Additionally, firearm homicide deaths were lower when states had checks for protective/restraining orders (IRR, 0.87; 95% CI, 0.79–0.95) and fugitive status (IRR, 0.79; 95% CI, 0.72–0.88). Firearm suicide rates were lower in states which had background checks for mental illness (IRR, 0.96; 95% CI, 0.92–0.99) as well as fugitive status and misdemeanors.

Noting significant variability in state and federal laws governing background checks, Sumner et al.[15] observed that no previous study had analyzed the effects of the differences among states in the background checks required for firearm purchase. Some states continue to use the Brady Act federal checks (official sunset 2004), some states still use a statewide agency to perform these checks, and other states mandate them to be performed at the local level. The authors hypothesized that some agencies would lack the resources to adequately check each of the Brady Act disqualifying criteria. Using negative binomial regression models, they studied the association between the classification of agencies conducting firearm background checks for each state 2002–2004 and firearm homicide and suicide rates for the same years. Results were controlled for age, race, unemployment, crime, income inequality, poverty, alcohol consumption, urbanization, and divorce rate. Performing local level checks, as opposed to state or federal checks, was associated with a 27% lower firearm suicide rate (IRR, 0.73; 95% CI, 0.60–0.89) and a 22% lower firearm homicide rate (IRR, 0.78; 95% CI, 0.61–1.01).

There has been particular attention on the role of restrictive gun licensing practices in reducing further intimate partner violence by restricting firearm access in those who have already been convicted of domestic violence. Vigdor and Mercy[14] evaluated data from Federal Bureau of Investigation crime reports and Supplemental Homicide Reports (SHR) from the same source from 1982 to 2002. They found that states with restraining order laws, that is, those that prohibit the subject of a restraining order from possessing a firearm, had a 8% reduction in the Intimate Partner Homicide (IPH) rate and a 9% reduction in the rate of IPH committed with a firearm. Bridges et al.[16] also looked at specific domestic violence statutes across 47 states using SHR data. Using point biserial correlation and multiple regression models controlling for urbanization, they found that statutes prohibiting abusers under restraining orders from purchasing handguns correlated with lower firearm IPH and family homicide rates. Other statutes, such as mandatory arrest laws, were not associated with lower IPH rates. Finally, Zeoli and Webster[17] performed a rigorous analysis of Federal Bureau of Investigation SHR data from 1979 to 2003, using a Poisson regression model which included covariates, such as state firearm laws, police staffing levels, alcohol excise taxes, firearm density, measures of sex equity, demographics, per capita income, and city homicide rates. The authors found lower IPH rates in states restricting possession of firearms among abusers (IRR, 0.81; 95% CI, 0.68–0.95) and those requiring mandatory arrest of perpetrators (IRR, 0.75; 95% CI, 0.62–0.92).

In 1995, Connecticut enacted a “permit-to-carry” law, which required firearm purchasers to obtain a permit through a law enforcement agency before sale. Rudolph et al.[20] examined the effect of this law on firearm homicide rates in the state, using states prelaw longitudinal trends and controlling for firearm density, law enforcement staffing, demographics, and income variables. They created a synthetic control or modeling of what Connecticut’s homicide rates would have been without the law, by comparing with rates in control states which had not enacted similar laws. They found a 40% lower firearm homicide rate than what would have been expected had the law not been enacted, and the divergence from the synthetic control began in 1999 and was sustained; they did not find an effect on nonfirearm homicide rates.

In 2007, Missouri repealed its permit to purchase law. Crifasi et al.[21] reported their analysis of the effects of both the Connecticut permit to purchase law and the Missouri law repeal on firearm suicide rates. Also, using synthetic modeling and controlling for states' prelaw longitudinal trends, firearm density, law enforcement staffing, demographics, and income variables, they found a 15.4% reduction in firearm suicide rates in Connecticut after the permit to purchase law was enacted, but a 16.1% increase in Missouri firearm suicides after repeal of a similar law. No consistent effect was seen on nonfirearm suicides.

In early 2016, Kalesan et al.[22] reported their results of a cross-sectional analysis of the effects of individual Brady Act provisions on firearm deaths. They adjusted for covariates, such as unemployment rate and baseline firearm death rates; however, they did not adjust for longitudinal trends in each state. The authors found that three provisions were associated with reduced firearm mortality: universal background checks (IRR, 0.39; 95% CI, 0.23–0.67), ammunition background checks (IRR, 0.18; 95% CI, 0.09–0.36), and identification requirement for firearm purchase (IRR, 0.16; 95% CI, 0.09–0.29). However, the authors also found an association between higher firearm death rates and certain provisions, including safety locks.

Still more recently, Kposowa et al.[23] examined the association between strictness of state gun control laws and suicide rates, as well as the effects of gun ownership and gun storage practices. Using US Centers for Disease Control and US Census Bureau data, controlling for explanatory variables, such as prevalence of gun ownership, population estimates of mental illness, and demographics, the authors found a consistent and linear correlation between strictness of gun control laws and firearm suicide rates.

Should CCLs be Used to Prevent Firearm Injuries? (PICO 2)

In recent years, much of the contemporary debate has centered on right to carry and CCLs and their variations across the country. We sought to examine the role of CCL programs in preventing or exacerbating firearm injuries. Of the 13 studies examined to answer this question,[23–36] 11 were population-based, longitudinal studies.[23–32 ][35 ][36] Two of those 11 showed decreases (6–8%) in firearm injuries in states with CCLs,[25 ][28] five showed no change or mixed effects,[26 ][27 ][29–32 ][35 ][36] and the final two showed increases in firearm injuries (3–26%).[24 ][31] Two studies focusing on licensees demonstrated that holders of a CCL who were subsequently arrested were more likely than matched controls to be perpetrators of IPHs, aggravated assaults, other firearm homicides, and sexual offenses.[33 ][34]

Article Summaries for PICO 2

McDowall et al.[24] were the first to study this issue, using interrupted time series analysis, analyzing data from multiple states and incorporating overall US homicide trends into the models as controls. They demonstrated that homicides increased after introduction of CCLs in four of the five areas studied, with a range of −12 to +75%, and an average change of +26%.

In 1997, Lott and Mustard[25] examined cross-sectional time-series data for US counties from 1977 to 1992. They estimated that if states without right to carry CCLs had adopted them in 1992, more than 1,500 murders could have been avoided yearly across the United States, a 7.65% decrease. Their models also suggested marked decreases in violent crime and costs associated with criminal activity if CCL laws were adopted. Their work has been heavily cited and is frequently credited as influencing the expansion of CCL programs across the United States.

Citing unaddressed missing data and inconsistencies in the Lott analysis, Black and Nagin[26] used the same data and conducted their own analysis. Using multivariate fixed-effects modeling, they found no net effect on homicides once year-to-year differences were factored in as a covariate, absent from Lott's original analysis. Using the same database, but including data through 1994, Ludwig[27]added the effect of minimum age requirements into a multivariate model and found that adult homicide rates were not impacted overall and actually increased after CCL laws in some states.

Olson and Maltz[28] were concerned with Lott's use of aggregation of state and local data and when the deaggregated the data with regards to weapon type, victim sex and age, and victim-offender relationship, they were unable to consistently reproduce Lott's findings. However, when multiple models were used and the data were restricted to counties with populations greater than 100,000 people, they found a 6.52% decrease in homicides, which they felt could be attributed to CCLs.

In a data set limited to Florida, Kovandzic and Marvell[29] used fixed-effects Poisson regression modeling to analyze homicide rates and found no effect or a slight increase after CCLs (0.005–0.104). Similarly, using Poisson regression modeling of National Center for Health Statistics data from 1979 through 1998, Hepburn et al.[30] did not find any consistent association between CCL licensing and homicide rates in the United States. Rosengart et al.[31] found a trend toward increased homicide rates after “shall carry” laws were implemented, but it was not statistically significant (RR, 1.11; 95% CI, 0.99–1.24). Of note, they also investigated specific gun regulation statutes, such as minimum age for purchase, and found no single regulation effective.

In a 2012 study, using a large, pooled US data set and looking specifically at “shall carry” versus “may carry” laws, LaValle and Glover[32] found that “shall carry” laws were associated with increases in homicide rates of 20% to 30%, but “may carry” laws were associated with decreases of 20% to 30%. In 2014, Ginwalla and colleagues[35] reported results of homicide rates preimplementation and postimplementation of Senate Bill 1108 in Arizona. The bill allowed for CCL and relaxed training regulations for firearm ownership. The authors found increases in firearm purchases and a 27% increase in firearm homicides (RR, 1.27; 95% CI, 1.02–1.58), without an increase in other violent crime.

Most recently, Aneja et al.[36] published a research white paper based on a 2004 publication from the National Research Council. The National Research Council article criticized the “more guns, less crime” data offered by Lott. In the Aneja article, the authors added additional county and state data, and many additional covariates, including incarceration rates and homicide rate fluctuations attributable to the crack cocaine epidemic. With these additional considerations, the authors concluded that the net effect of CCLs was to increase homicide rates by 3%, as well as increasing aggravated assaults and rapes by up to 38%.

The final two papers included in this analysis specifically addressed the possibility of CCL holders as perpetrators, particularly given the increased homicide rates found after CCL implementation in some studies. In 2013, the Violence Policy Center published a retrospective case series examining CCL holders and mass shootings in the U.S. from May 2007 until October 2013.[33] They found that CCL holders were involved in at least 386 fatal shootings during the study period, leading to at least 540 deaths including 14 law enforcement officers. Subsequent to this work, the Violence Policy Center Website has maintained updated information on CCL holders, homicides, mass shootings, and suicides.

In a more scientific analysis, Phillips et al.[34] explored the differences in criminal convictions over 10 years between holders and nonholders of a CCL permit in the state of Texas. Although license holders were far less likely than nonholders to be subsequently convicted of a crime, their crimes tended to be more focused on those that would occur with the increased availability of a weapon. CCL holders were 2.2× more likely to commit sexual offenses, 4.7× more likely to commit deadly conduct, and 2.3× more likely to commit a homicide.


The enormity of the human and economic toll of gun violence cannot be overstated. However, methods to prevent firearm injuries are controversial, particularly because many of these methods involve some form of restricted access to guns, which some argue is a violation of our constitutional right to bear arms. Indeed, many people have argued that increased weapons in the population should have a “crime suppressive” effect, further polarizing the discussion. The goal of this systematic review was to critically assess the evidence regarding legislative efforts to decrease access to weapons, specifically restrictive licensing and CCLs.

We encountered many challenges in our data collection and analysis, in particular, the heterogeneity of studies, methodologies used, different covariates for each study, differing modeling strategies, and even the differences between the laws themselves and state enforcement. For these reasons, we did not attempt a meta-analysis, nor did we attempt a forest plot of our results, given that the contextual nature of each study precluded a simple visual comparison. The overall quality of evidence with regards was weak. There were no randomized controlled clinical trials, some case-control studies, mostly retrospective data and some reviews. The risk of both publication bias and insufficient control for confounders in the study samples was significant. Finally, several authors, notably Webster and Hemenway, contributed to many of the articles. Therefore, one cannot discount the possibility of investigator or publication bias.

However, though the quality of each individual study was weak, the magnitude and direction of the effect sizes were sufficiently similar to allow us to draw conclusions for both PICO questions.


Should Restrictive Licensing Policies be Used to Prevent Firearm Injuries? (PICO 1)


We recommend the use of restrictive licensing to decrease the incidence of firearm injuries.

The overall gun-murder rate has dropped by approximately 15 percent between 2006–2007 and 2009–2010 in a majority of the nation's 50 largest cities. Multiple, large, population-based studies have demonstrated an association between more stringent firearm purchase and ownership restrictions and firearm injuries. Although all of the studies are ecologic, the net effect and the magnitude of the net effect is significant and believable. It has biologic plausibility, as access to firearms has been linked in cohort studies to increased risk of both suicide and domestic homicide.[37 ][38] The strongest studies were rigorously analyzed for crucial covariates, such as state longitudinal firearm injury trends, impact of the crack cocaine epidemic, and effects of mass incarceration. With respect to individual provisions, background checks appear to be particularly impactful, but it must be noted that the data are mixed on other provisions, such as gun safety locks. These studies are also supported by the international experience, where more stringent gun control laws have been associated with lower firearm homicide and suicide rates, and fewer mass shootings.[39–42]

Should Concealed Carry Laws be Used to Prevent Firearm Injuries? (PICO 2)


We recommend against the use of CCLs solely as a strategy to decrease the incidence of firearm injuries within populations.

At the current time, the data do not support a “crime suppressive” effect of CCLs, and, in fact, may increase firearm injuries. However, no definitive conclusions can be drawn at this time, given the data limitations and mixed results. Crime rates do appear to influence applications for concealed carry permits, which could lead to a worrying cycle of increased concealed carrying, and further increases in firearm injury rates.[43] We suggest that ongoing longitudinal cohort studies of concealed carry permit holders continue, as some licensees were found more likely to commit assault and firearm-related crimes than case-matched controls in one study.

Using These Guidelines in Clinical Practice

Most trauma surgeons in the United States are disturbingly familiar with the tragic effects of gun violence. As part of our duty to injury prevention, we practitioners are also citizens, and should consider the effects of local, state, and federal laws and ordinances governing restrictions on ownership and carrying of firearms, because they ultimately affect firearm injuries.


In summary, after evaluating the best available data, this committee found an association between more restrictive licensing, criminal background checks, and lower firearm injury rates. We could find no consistent effect of CCLs. Of note, the varied quality of the available data demonstrates a significant information gap, and this committee recommends further research to strengthen future evidence based guidelines. Future updates will require reevaluation of these and other potentially useful injury prevention strategies.


M.C., A.E., P.V., and A.B.C. designed this study. M.C. and P.V. conducted the literature search. M.C., A.E., P.V., W.G., S.A., E.B., A.B.C., T.D., S.F., S.G., M.H., D.J., K.L., W.S., and P.P. graded the evidence. M.C., A.E., P.V., W.G., S.A., E.B., A.B.C., A.D., T.D., S.F., S.G., M.H., D.J., K.L., W.S., and P.P. contributed to data interpretation. M.C., A.E., P.V., and W.G. prepared the manuscript, which M.C. edited.


We thank medical librarians at Northwestern University and University of Florida College of Medicine Jacksonville for their assistance in performing literature searches.


The authors declare no conflicts of interest.


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