It has been 15 years since Florida enacted its stand your ground (SYG) law. Since then, a growing number of states have followed suit, and the research community has generated a growing body of literature to try to understand their effects. At the Stand Your Ground Project (SYGP), we have been working for several years to locate, analyze and synthesize this research, as well as conducting new analyses of our own. In this blog, we provide an overview of recent developments in SYG laws as well as a description of the findings from our most recent study (Yakubovich et al., [2021] – forthcoming in the American Journal of Public Health, available online on 18th February 2021). We have drawn three main conclusions from our review of studies published so far:
a. Stand your ground laws have not reduced violent crime across the US. There is no evidence that stand your ground (SYG) laws have improved public safety by deterring violent crime.
b. Stand your ground laws are associated with increases in lethal violence in some states. The association between the enactment of stand your ground laws and increased homicide rates has been best evidenced in the case of Florida (see here, here, and here). But studies find a consistent association with increased violence across when effects are averaged across all states in which the laws have been enacted (e.g. using vital statistics or uniform crime statistics).
c. Studies suggest that there are stark racial inequities in the application of stand your ground laws. Though limited in number, all existing studies show that cases end in conviction more often when the victim was White – especially when the claimant is from a racial minority. There is less research on these inequities outside of Florida (further research is required), but initial evidence suggests these findings exist across other states.
New SYG laws 2021
One month into 2021, and it is already proving to be a busy year for news about SYG laws. On Monday 4th of January, Ohio Governor Mike DeWine signed the states “Stand your ground” bill into law, despite previously committing to only sign the law if a series of common-sense gun safety measures (e.g. fines for violent offenders caught with guns) were also enacted:
"I have always believed that it is vital that law-abiding citizens have the right to legally protect themselves when confronted with a life-threatening situation.…I am very disappointed, however, that the legislature did not include this bill essential provisions that I proposed to make it harder for dangerous criminals to illegally possess and use guns”
On Tuesday 19th of January, Arkansas Senate Bill 24, passed the Senate with 27-7 vote and will now pass to the Senate floor for consideration by the House Judiciary Committee. Like Ohio and other states previously, the introduction of the SYG bill is proving divisive. The bill has been opposed in an open letter from 79 faith leaders from the state, who strongly oppose the law on the grounds that SYG laws “encourage people to resolve issues with violence”, are associated with a “senseless loss of life”, and disproportionately affect communities of colour. Despite such objections, supporters of the bill propose a range of benefits. Speaking to Fox News, Representative Aaron Pilkington, a primary sponsor of the bill, cited improvements in perceptions of safety and a reduction in violence in support of the laws.
“I think you are going to see a decrease in the amount of assaults and things like that with deadly weapons”Rep. Aaron Pilkington (2021), Fox News
The public safety benefits of SYG laws are regularly touted to justify these laws. But SYG laws have been active in other states for over 10 years. Does the evidence support these, or other claims?
What does the evidence say?
Since 2019, the SYG project research team has been conducting a detailed review of research examining the impact of expansions (or restrictions) on self-defense laws. In a study forthcoming in the American Journal of Public Health we examined over 20,000 academic papers and research reports to collect and synthesize estimations of the impact of changes to self-defense laws on health (e.g. homicide), criminal justice (e.g. crime), and socio-legal (e.g. prosecution) outcomes.
We found 25 studies meeting our pre-specified search criteria. All of these studies focussed on U.S. SYG laws. The studies were diverse, using a range of different methodological designs, statistical analyses, outcomes, and specifications of outcomes. However, as shown in the figure below (see Figure 1), the existing evidence is clear:
Studies show no evidence of a deterrent effect on violent crimes; in fact, studies examining these outcomes tend to show that enacting SYG laws is associated with increases, rather than decreases, in harm.
Studies suggest that on average, across states, the enactment of SYG laws are associated with modest increases in the rates of violence (up to 14%). Studies examining Florida found large, statistically significant increases in homicide rates (24-45%) following the enactment of the law in 2005.
Self-defense cases involving SYG claims in Florida ended in conviction more often when the victim was White and especially when the claimant was a racial minority. These racial inequities were not explained by case characteristics (including whether the victim was armed) or SYG considerations (for instance, the proportionality of force).
Figure 1: Graphical synthesis showing percent change in violent outcomes of laws expanding the right to use deadly force in self-defense outside the home.
Footnotes: (a) Including studies that analyzed gun deaths excluding suicide. (b) The most conservative estimates are included for Gius et al. (2016). The most liberal estimates are provided in Table A7 (see paper appendix) – results were consistent, with liberal estimates suggesting null to small positive effects. (c) The study used IHS rather than log transformation. (d) There are three iterations of these analyses (two working papers and one peer-reviewed publication). We include the latter in this review as the most up-to-date analyses. White boxes represent estimates for outcomes conceptualized as ‘negative controls’.
Figure 1 shows a forest plot in which the most conservative estimates from studies examining the impact of the laws on: firearm homicide, total homicide, aggravated assault, total robberies, justifiable homicide, non-firearm homicide. Panel (A) shows estimates for those studies examining the impact of SYG laws across states, and Panel (B) summarises estimates in Florida-specific studies. We constrained the figure to include only those outcomes for which two or more studies produced comparable estimates. In total, the 25 studies yielded estimates for 40 separate outcomes.
The horizontal axis in the figure above represents the range of estimates of the relative percent change in rates for different outcomes (from -50% decrease, to +50% increase). The study is identified by the first author’s name and year of publication on the left, and the estimate (with 95% confidence intervals) is shown on the right. The point estimates are represented by the markers in the graph, with the horizontal bars showing the confidence intervals (which indicate uncertainty of the estimates). The vertical line in the graph is the line of no effect (0% change).
Taken together this figure shows that, while there is variation in the size of the estimated size of effects across studies, the evidence suggests that enacting SYG laws is associated with increases in violence. To date we have found little evidence to support the claim that SYG laws may be associated with protective effects on public safety. The impact of these laws is most pronounced in Florida-specific studies. While USA-wide studies are more muted, this suggests there may be variation across states, which is something we are investigating in other forthcoming work.
Less than a quarter of the evidence considered differences in the impacts of SYG laws by race or other sociodemographics. This is noteworthy because of the longstanding concern that SYG laws exacerbate violence experienced by communities of colour. However, the few available studies suggest similar increases in homicide rates across race and sex across states. Several studies examining the outcomes in homicide cases involving claims of self-defense following the enactment of SYG laws found that cases ended in conviction more often when the homicide victim was White. Such effects were even more pronounced when the defendant was from a racial minority. Therefore there appears to be some evidence that these laws amplify racial bias in the criminal justice process in rulings on stand your ground cases.
Conclusion: what we know
During the last 15 years, SYG laws have been subject to scientific investigation by multiple studies, from different researchers, spanning several different fields. In a forthcoming research paper (see below) we present the results of a systematic review of this literature, the findings of which have been summarised briefly above. Generating reliable estimates of the effects of policies and laws can be very challenging and studies examining SYG laws are no exception to this (as we discuss at greater length in the manuscript). Despite the variation in studies, their design, and the estimates they generated, the results represent a clear picture that suggests that there is little evidence of a protective effect of SYG laws on public safety.
Claims that enacting these laws will result in positive outcomes for violence or crime are not represented by the weight of existing evidence. On the contrary, most studies show that SYG laws tend to be associated with increases in violence and crime outcomes and appear to exacerbate racial disparities in how cases involving self-defense are resolved.
Further reading
Yakubovich, A. R., Degli Esposti, M., Lange, B. C. L., Melendez-Torres, G.J., Parmar, A., Wiebe, D., & Humphreys, D. K. (2021) Effects of laws expanding civilian rights to use deadly force in self-defense on violence and crime: A systematic review. Forthcoming in American Journal of Public Health (March 2021).