Publications to date
Effects of Laws Expanding Civilian Rights to Use Deadly Force in Self-Defense on Violence and Crime: A Systematic Review
Alexa R. Yakubovich, Michelle Degli Esposti, Brittany C. L. Lange, G. J. Melendez-Torres, Alpa Parmar, Douglas J. Wiebe, and David K. Humphreys
American Journal of Public Health, doi: https://doi.org/10.2105/AJPH.2020.306101
Since 2005, most US states have expanded civilian rights to use deadly force in self-defense outside the home. In most cases, legislation has included removing the duty to retreat anywhere one may legally be, commonly known as stand-your-ground laws. The extent to which these laws affect public health and safety is widely debated in public and policy discourse. We searched MEDLINE, Embase, PsycINFO, Scopus, Web of Science, Sociological Abstracts, National Criminal Justice Reference Service Abstracts, Education Resources Information Center, International Bibliography of the Social Sciences, ProQuest Dissertations and Theses, Google Scholar, National Bureau of Economic Research working papers, and SocArXiv; harvested references of included studies; and consulted with experts to identify studies until April 2020. We identified 25 studies that estimated population-level impacts of laws expanding civilian rights to use deadly force in self-defense, all of which focused on stand-your-ground or other expansions to self-defense laws in the United States. The existing evidence contradicts claims that expanding self-defense laws deters violent crime across the United States. In at least some contexts, including Florida, stand-your-ground laws are associated with in- creases in violence, and there are racial inequities in the application of these laws.
Increasing adolescent firearm homicides and racial disparities following Florida’s ‘Stand Your Ground’ self- defence law
Michelle Degli Esposti, Douglas Wiebe, Jason Gravel, David K Humphreys
Injury Prevention doi: 10. 1136/ injuryprev- 2019- 043530
Establishing whether specific laws impact rates of firearm homicide in adolescents is critical for identifying opportunities to reduce preventable adolescent death. We evaluated Florida’s Stand Your Ground law, enacted October 2005, using an interrupted time series design from 1999 to 2017. We used segmented quasi- Poisson regression to model underlying trends in quarterly rates of adolescent (15–19 years) firearm homicide in Florida and disaggregated by race (Black/White). We used synthetic and negative controls (firearm suicide) to address time- varying confounding.
Regional differences in the impact of the “Stand Your Ground” law in Florida
Benjamin Ukert, Douglas Wiebe, David K. Humphreys
Preventive Medicine doi: 10.1016/j.ypmed.2018.08.010
In October 2005, Florida relaxed restrictions on the use of lethal force in self-defense with the Florida stand your ground law (SYG). We examined whether and how the impact of the Florida SYG varied based on the demographic and economic conditions of each of its counties. Using data from the Florida Universal Crime Reports on homicides and firearm homicides from 1999 to 2014, we found that the impact differed significantly by county urbanization, unemployment, and pre-law homicide rates. The largest increases in homicide and firearm homicide occurred in proportionally safer, richer, and less ethnically diverse suburban counties. These findings reveal that the law may have had the opposite effect than intended, and more strongly impacted counties considered safe, suburban and economically successful.
Association Between Enactment of a “Stand Your Ground” Self-defense Law and Unlawful Homicides in Florida
David K. Humphreys, Antonio Gasparrini, Douglas Wiebe
JAMA Intern Med doi:10.1001/jamainternmed.2017.3433
Our 2017 study on the impact of Florida’s “Stand Your Ground” self-defense law on homicide and suicide by firearm1 has been criticized for not distinguishing between “unlawful” homicide (i.e. murder) and “justifiable” homicide (i.e. lawful use of lethal force). Using an interrupted time series design, we found an abrupt and sustained increase in the monthly homicide rate of 24.4% (31.6% for homicide by firearm). However, critics have argued that if the increase in the homicide rates resulted from an increase in justifiable homicides, the law may be working as intended. To assess such concerns, we acquired additional data and conducted additional analyses.
Evaluating the Impact of Florida’s “Stand Your Ground” Self-defense Law on Homicide and Suicide by Firearm An Interrupted Time Series Study
David K. Humphreys, Antonio Gasparrini, Douglas Wiebe
JAMA Intern Med. doi:10.1001/jamainternmed.2016.6811.
In 2005, Florida amended its self-defense laws to provide legal immunity to individuals using lethal force in self-defense. The enactment of “stand your ground” laws in the United States has been controversial and their effect on rates of homicide and homicide by firearm is uncertain. The aim of this study was to estimate the impact of Florida’s stand your ground law on rates of homicide and homicide by firearm. We found that the implementation of the law was associated with a significant 24.4% increase in homicides (relative risk [RR], 1.24; 95%CI, 1.16-1.33) and 31.6% in homicides by firearm (RR, 1.32; 95% CI, 1.21-1.44) but no change in rates of suicide or suicide by firearm.