In 2005, Florida legislators passed the nation’s first “Stand Your Ground” law, expanding legal immunity for residents to use lethal force when they believe they’re being threatened. A decade later, a new study finds that Florida has experienced a significant increase in homicides, while states without such laws have not.

“From a public health perspective, we were shocked that in a given area, rates of people dying changed so abruptly and in such a sustained way,” study co-author Douglas Wiebe, an associate professor of epidemiology at the University of Pennsylvania Perelman School of Medicine, told me. “These are people dying who otherwise wouldn’t have died. That is what is most profound about our findings.”

Published earlier this week in JAMA Internal Medicine, the study found that in the law’s wake, Florida’s monthly homicide rate experienced an “abrupt and sustained” increase of nearly 25 percent, while the monthly rate of homicide by firearm went up more than 31 percent. No change in overall homicide rates or firearm-related homicide rates were found in the four comparison states — New York, New Jersey, Ohio and Virginia — that don’t have Stand Your Ground laws. In fact, researchers found that in the handful of years prior to implementing the law, Florida had been experiencing a slight decline in monthly rates of homicides. Following implementation of the law, both homicide rates and homicides by firearm increased in the Sunshine State.

“I think we have strong and sufficient evidence to suggest that we should consider repealing this law because it seems to have produced an increase in homicides,” said Wiebe, who also serves on the Executive Committee of Penn’s Injury Science Center. “We should also now go and rigorously evaluate what’s happening in other states (that adopted similar laws), but we don’t need to wait until then to consider acting in Florida.”

According the study, Florida’s Stand Your Ground law “increased the scope of self-defense claims by creating a ‘no duty to retreat’ rule when individuals ‘reasonably believed’ that force was necessary to prevent harm to themselves or others.” While residents already had the right to not retreat if threatened in their own homes, Florida’s new law extended the “no duty to retreat” rule to the public sphere. In fact, the Florida law allows residents to use lethal force even if the shooter is the one who instigated the confrontation that led to him or her feeling threatened. The law also made it legal to use lethal force in defense of property, such as stopping a car theft. To date, 23 other states have adopted a Stand Your Ground law as well.

So, why are Wiebe and his fellow researchers so confident in the association between the expanded self-defense law and Florida’s homicide increase? It’s all in the study design. They used 15 years’ worth of data from the Wide-Ranging Online Data for Epidemiologic Research portal at the Centers for Disease Control and Prevention, gathering monthly data on Florida homicide rates from 1999 to 2014. They examined that data using an interrupted time series design — a design in which an intervention, in this case the enactment of Stand Your Ground, occurs at a specific point in time and so researchers can more confidently compare before-and-after data. The study authors also took into account cyclical trends in homicides rates that typically correspond to certain seasons and months, and they picked a handful of control states without Stand Your Ground laws for comparison purposes.

The result? A large effect on gun homicides across population groups — “it was consistent across the board,” Wiebe said. The study found increases in homicides in all demographic groups, though the effect wasn’t evenly distributed. In particular, enactment of Florida’s Stand Your Ground law was associated with a nearly 29 percent increase in overall homicides among whites; a 20 percent increase among blacks; a nearly 32 percent increase among people ages 20 to 34; a nearly 14 percent increase among people ages 35 and older; a 28 percent increase among males; and a more than 13 percent increase among females. Similar trends were found for gun-related homicides. (When you look at the graphs included in the study, the homicide increases are immediately apparent. For both overall homicides and gun-related homicides in Florida, there’s an abrupt and large spike in 2005 when Stand Your Ground became law.)

Researchers also found no significant changes in homicide rates or gun-related homicide rates in comparison states during the same time period. Still, the researchers wondered: Did anything else happen during that time period that could have so abruptly impacted Florida’s homicide rate? Perhaps, it was related to the economy and the Great Recession. So, said Wiebe, they examined Florida’s suicide rate — a rate that’s typically sensitive to economic and social trends — and could offer a clearer picture of possible contributors to the increased homicide rate. The results: no changes in Florida’s suicide rate between 2005 and 2014.

Wiebe and study co-authors David Humphreys and Antonio Gasparrini write: “Our findings support the hypothesis that increases in the homicide and homicide by firearm rates in Florida are related to the stand your ground law.”

“We were surprised,” Wiebe told me. “We tested this possibility because the scenario suggests this could happen. But you go into this kind of research thinking it’s a bit of a long shot to find evidence of these possibilities. So it was genuinely surprising to see such a large, abrupt and sustained shift. …It’s not often you see such compelling and strong evidence as this.”

Wiebe noted that this is the first study to examine the impact of a Stand Your Ground law using such rich and complex data spanning so many years. However, he said he’s also not surprised it’s the first, considering the dearth of funding for such research. He said this study, which required “an enormous amount of effort,” was done without the support of funding.

“This is a medical, public health and criminal justice problem happening in an area of interest for which there is very little funding available to learn more,” Wiebe said. “This study suggests we need more research dollars at the federal level to support this kind of work.”

For a full copy of the new study, visit JAMA Internal Medicine.

Kim Krisberg is a freelance public health writer living in Austin, Texas, and has been writing about public health for nearly 15 years.

Comments

  1. #1 SteveP
    November 19, 2016

    ” In fact, the Florida law allows residents to use lethal force even if the shooter is the one who instigated the confrontation that led to him or her feeling threatened.”

    So it would seem that gun owners can now threaten people verbally, potentially get them into a position where they feel that they have to defend themselves by some physical means, and the gun owner can then shoot them without penalty? I suspect that there must be something else missing in this description…. or……. I wonder how many of these new homicides were cleverly set up to achieve the desired outcome by gun owners of murderous intent?

  2. #2 dean
    November 19, 2016

    individuals ‘reasonably believed’ that force was necessary to prevent harm to themselves or others.”

    There is the effing problem. How incredibly high is the bar that needs to be crossed in order to show a person did not “reasonably believe” something.

  3. #3 rork
    November 20, 2016

    Still a bit skeptical. Wondered how homicides not using guns changed. Also, there are several other states whose data should replicate that of Florida if they are correct.
    They mentioned ” 1 study that used a difference in differences design to examine changes in 20 states that enacted stand your ground laws between 2000 and 2010 compared with all nonparticipating states found an associated 8% increase in homicide” – that effect is much smaller than for this new paper. Why? With data on many states we might be able to put terms in the model that explains why the effect is larger in some states than others.
    Confounding example: Maybe there’s a certain kind of person that has become more violent, they tend to be better represented in some states, those states also tended to pass these laws.

  4. #4 Helianthus
    November 22, 2016

    @ rork

    Maybe there’s a certain kind of person that has become more violent

    The numbers from this Florida study would suggest this person to be young, male and white.

  5. #5 Anon
    November 28, 2016

    How this paper passed peer review and why it has not already been withdrawn is a question left to the reader.

    The three authors of this paper that examines a Florida self-defense law do not claim any expertise whatever in the law, and consequences of their (willful?) ignorance are painfully evident throughout the paper. The absence of a claim to legal expertise is made clear when one looks at departments for which the authors work: “Social Policy and Intervention,” “Hygiene and Tropical Medicine,” and “Biostatistics and Epidemiology.” Law? Yeah, not so much.

    That the paper was written not for purposes of scientific advancement or public policy utility but solely to push the authors’ ideological preferences is made apparent by the their statements to the press outside the highly constrained bounds of the paper itself.

    One of the authors, Antonio Gasparrini, claims in the UK’s Daily Mail that the study shows how Florida’s Stand-Your-Ground law drives increased murders.

    “This study highlights how Stand Your Ground is likely to be a cause of the rise in Florida murders, and provides crucial information which may influence future decision-making that affects wellbeing in the US and abroad,” said co-author Antonio Gasparrini of the London School of Hygiene and Tropical Medicine.”

    In fact, the paper makes no particular effort whatever to study murders, as explained below.

    The paper’s lead author, David Humphreys, is cited in the Wall Street Journal as hoping that “the study would compel officials to review the law and consider whether it should be amended or repealed.” This is a bizarre hope given that his paper is equally consistent with Florida’s Stand-Your-Ground law having been an unmitigated success as it is with a law that ought to be repealed. As explained below, Humphrey’s hope that “Stand-Your-Ground” be repealed, in the context of his own paper, is entirely consistent with a desire for an increase in the murders, maimings, and rapes of innocent people.

    In short, the paper appears to be nothing more than the usual faux “science” anti-self-defense propaganda of the sort that has long ago become familiar to gun owners across America, and which years ago led to Congress appropriately denying taxpayer funds for “scientists” turning out similar “research” tripe in the past.

    Collectively the authors make numerous substantive errors, any one of which would gut any claimed scientific or public policy utility of their paper, but in the interests of brevity I will focus on just two.

    JAMA Paper Fails to Distinguish Between Homicide and Murder

    The paper itself authors claim that the passage of Florida’s Stand-Your-Ground is correlated with an increase in the state’s homicides. Indeed, a one-time spike in homicides did apparently occur in the year immediately following the law’s passage.

    To take from this that the law had negative public policy consequences—as implicitly claimed by author Humprey’s in his call for repeal—or that the law has led to an increase in murders—as explicitly claimed by author Gasparrini—is such a high degree of nonsense as to qualify as academic malfeasance.

    “Homicide” and “murder” are not synonymous terms. The WSJ notes that the CDC defines “homicide” as “one person causing the death of another with intentional force but not necessarily an intent to kill.” It is important to note that there is nothing about this definition that implies anything unlawful whatever. While it is definitionally true that all murders are homicides, it is not true that all homicides are murder. Indeed, not only are many homicides not murder, many are not merely legally justified but actually a social good.

    This is easily illustrated. A rapist who kills his rape victim has (in addition to committing rape) committed a homicide—and it is also true that this homicide is a murder, an unlawful, unjustified killing of another person. In contrast, should the rape victim manage to foil her rapist by killing him, she has also committed a homicide—but her homicide is a justified killing in self-defense, not an unlawful murder. Both killings are homicides, but the former is murder and the latter is not.

    When the authors of this “scientific” paper thus claim to have found that Florida’s Stand-Your-Ground law is linked to an increase in “homicides,” they have failed to find anything of either scientific or public policy utility whatever. Their research tells us absolutely nothing about what portion of these homicides are unlawful murders and which are legally justified killings.

    To put it another way, for all anyone can tell from this paper every single one of the purportedly “Stand-Your-Ground” homicides was a lawful killing of a criminal predator who would otherwise have been successful in murdering, maiming, or raping an innocent victim. In other words, for all the authors’ claims that Stand-Your-Ground has led to an increase in unlawful violence it is equally as likely that the law has led to a decrease in unlawful violence.

    JAMA Authors Fail To Understand “Stand-Your-Ground” as Law

    A second major error evident in the paper is the author’s apparent ignorance of Stand-Your-Ground as law. They helpfully provide a table listing 23 of the 50 American states has being “Stand-Your-Ground” states. By the only useful definition of Stand-Your-Ground, however—that is, that a defender has no legal duty to attempt a safe retreat before acting in self-defense—there are in fact 35 Stand-Your-Ground states. In fact, only 15 states impose a legal duty to retreat before acting in self-defense.

    Further, the authors claim to use as a control a set of four American states that do generally impose a legal duty to retreat. In fact, only three of the chosen states generally impose such a legal duty. The fourth “control” state, Virginia, imposes a legal duty to retreat only if the defender “contributed to the affray”—in other words, only if the defender is not a genuinely innocent victim of a criminal attack. Every state in the country, however, requires that an aggressor in a fight must retreat from the confrontation before they can claim self-defense for their use of defensive force. The author’s choice of Virginia as a contrast to Florida thus exposes both their misunderstanding of Virginia law specifically and the legal constraints imposed on claiming self-defense broadly.

  6. #6 Jim
    United States
    January 4, 2017

    Interestingly, they don’t appear to have looked that the numbers relative to any other factors. They simply looked at the raw number of homicides.

    But the homicide *rate* for Florida hasn’t really budged during the same time period. 5.0/100,000 in 2005. 5.1/100,000 in 2015.

    Homicide rates decreased in all 4 of the control States although again, only marginally in 2 of them.

    This is because Florida’s population increased by almost 4 million people over that same 10 year period while it held steady in all 4 control States.

    It took me less than 5 minutes to find these other stats – all of which would have made this article much more informative if they had been included.