Florida’s Red Flag Gun Law and Firearm and Nonfirearm Homicide and Suicide Rates

Abstract

This study estimates the association between Florida’s red flag law enactment and firearm and nonfirearm homicide and suicide rates.

Firearm homicides are a leading cause of death in the US among individuals younger than 44 years,¹ with over 21 000 deaths from mass shootings between 2014 and 2022.² In response to the 2018 Parkland high school shooting that killed 17 people, Florida’s legislature enacted a red flag law permitting the temporary removal of firearms by law enforcement officers from individuals posing a danger to themselves or others. Florida is one of the few politically conservative and largely profirearm states to pass a law restricting gun ownership.³

Research into how red flag laws affect firearm-related homicide mortality is scant, with inconclusive findings.⁴ However, red flag laws may reduce firearm-related suicide mortality.^4,5 We estimated the association between Florida’s red flag law enactment and firearm and nonfirearm homicide and suicide rates.

Methods

We used data from CDC WONDER on state-level firearm and nonfirearm homicide and suicide mortality rates from 2009 to 2021. We used the augmented synthetic control method to construct a weighted combination of 19 politically conservative states lacking similar gun laws to serve as a matched control for Florida. We excluded 2018, the year of law enactment. Models estimated yearly mortality rate ratios (MRRs) and the mean MRR during the post–law enactment period 2019 to 2021 comparing Florida with its synthetic control. Models included state fixed effects and adjusted for state-level sociodemographic and economic covariates, with statistical significance indicated by jackknife+ 95% CIs excluding 1 (eAppendix in Supplement 1). Analyses were completed in R version 4.4.0. Because the study involved only state-level publicly available data, the Columbia University institutional review board determined that it did not meet the criteria to be considered human subjects research.

Results

Florida’s firearm homicide rate increased from 4.51 deaths per 100 000 population in 2017 to 5.28 in 2021 compared with 4.50 to 6.85 for its synthetic control; Florida’s nonfirearm homicide rates decreased slightly from 1.53 to 1.46 compared with 1.56 to 1.49 for its synthetic control (Figure 1). During this period, Florida’s firearm suicide rates increased from 8.21 to 8.85 deaths per 100 000 compared with 8.56 to 9.31 for its synthetic control; nonfirearm suicide rates decreased in Florida (7.17 to 6.53) and its synthetic control (7.41 to 7.07).

Figure 1. Mortality Rates Over Time for Florida, Synthetic Control, and Individual Control States.

The year of Florida’s law enactment, 2018, was excluded from analyses to account for lagged effects. Vertical dashed line indicates year succeeding law enactment. Mortality rates for the synthetic control were calculated as a weighted mean using weights from augmented synthetic control models intended to balance both preperiod outcomes and covariates. All augmented synthetic control models included the following state-level covariates: proportion younger than 18 years, proportion Black or African American, proportion aged 18 years or older living at or below the poverty level, mean per capita individual income, proportion living in metropolitan statistical areas, and expenditure on police capital outlay. The proportion Black or African American was classified and defined by the US Census Bureau and included because state-level racial composition is associated with mortality.

Firearm homicide yearly MRRs comparing Florida with its synthetic control were less than 1 after 2018 (lower than expected), and significantly so by 2021 (yearly MRR, 0.77; 95% CI, 0.69-0.83) (Figure 2). Across the postlaw period, Florida’s red flag law was associated with an 11% reduction in firearm homicide rates (mean MRR, 0.89; 95% CI, 0.79-0.96), equivalent to 0.73 fewer deaths per 100 000 population per year (calculated as mean difference in postperiod rates in Figure 1 between Florida and its synthetic control). Nonfirearm homicide yearly MRRs fluctuated after 2018 and were similar to expected levels across the postlaw period (mean MRR, 1.03; 95% CI, 0.85-1.16). Although firearm suicide and nonfirearm suicide yearly MRRs decreased after 2018, neither was significantly lower than expected across the postlaw period (firearm suicide mean MRR, 0.97 [95% CI, 0.90-1.05]; nonfirearm suicide mean MRR, 0.95 [95% CI, 0.80-1.15]).

Figure 2. Estimated Yearly Mortality Rate Ratios Between Florida and Its Synthetic Control.

The year of Florida’s law enactment, 2018, was excluded from analyses to account for lagged effects. Vertical dashed line indicates year succeeding law enactment. Shaded areas represent 95% CIs for yearly estimates in the post–law enactment period. All augmented synthetic control models included the following state-level covariates: proportion younger than 18 years, proportion Black or African American, proportion aged 18 years or older living at or below the poverty level, mean per capita individual income, proportion living in metropolitan statistical areas, and expenditure on police capital outlay. The proportion Black or African American was classified and defined by the US Census Bureau and included because state-level racial composition is associated with mortality.

Discussion

Although firearm homicide mortality increased after Florida’s red flag law enactment, this increase was lower than expected compared with its synthetic control, resulting in an 11% rate reduction (0.73 fewer deaths per 100 000). There were no differences from expected mortality rates for nonfirearm homicide, firearm suicide, or nonfirearm suicide.

Since 2018, 10 965 petitions have been filed under Florida’s red flag law in 93% of counties. Petitions increased from 1192 in 2018 to 2907 in 2022, exceeding those of states with comparable laws.³ The magnitude of the estimated association is plausible, given estimates from studies on other gun control legislation.⁶

Limitations include that the validity of the results depends on whether the synthetic control was an appropriate proxy for Florida in the absence of the red flag law, which may not be the case if, for example, Florida’s response to the COVID-19 pandemic differed from that of control states in ways that affected firearm homicides. Additionally, this study cannot definitively attribute the reduction in expected firearm homicide rates to the red flag law vs other societal changes after the Parkland homicides. However, findings suggest that red flag laws may reduce the growing burden of firearm homicides.

Section Editors: Kristin Walter, MD, and Jody W. Zylke, MD, Deputy Editors; Karen Lasser, MD, MPH, Senior Editor.

Supplement 1.

eAppendix. Supplemental Methods

Supplement 2.

Data Sharing Statement