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Criminal Justice, Municipal

Does strengthening self-defense law deter crime or escalate violence?

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After Trayvon Martin was shot and killed by neighborhood watch volunteer George Zimmerman in Florida, February 2012, a national debate began over how such a tragedy could have befallen an unarmed teenager. Beginning with Florida in 2005, 24 states enacted so-called “stand your ground” laws that widen the scope for the justified use of lethal force by citizens. In the past, self-defense laws have adhered to the principle that one has a duty to retreat from an assailant before using force. But this recent legislation, known as “castle doctrine laws” — under the theory that a home is one’s “castle,” and therefore can be defended — have relaxed this principle, allowing the use of deadly force in one’s home as well as some public spaces.

Following Zimmerman’s acquittal, the effectiveness of these laws and the outcomes produced continue to be debated, and the available research data have some insights. (It is worth noting that it has subsequently become controversial what exact role “stand your ground” laws may or may not have played in the Zimmerman case and trial.)

A 2012 paper for the National Bureau of Economic Research, “Does Strengthening Self-Defense Law Deter Crime or Escalate Violence? Evidence from Castle Doctrine,” examines the effects such laws have on illegal activity and rates of lethal incidents. Researchers from Texas A&M University used FBI state-level crime data from 2000-2009 to test the effects of castle doctrine laws and compare outcomes across states.

The study’s findings include:

  • States that adopted castle doctrine laws saw a 7% to 9% increase in murder and manslaughter incidents compared to states that did not adopt such laws. This percentage increase “translates into an additional 500 to 700 homicides per year nationally across the states that adopted castle doctrine.”
  • Adoption of castle doctrine laws resulted in a 17% to 50% increase in justifiable homicides, with justifiable homicide defined by the FBI as “the killing of a felon, during the commission of a felony, by a private citizen.” The authors note, however, that this result is suggestive, not conclusive.
  • Adoption of castle doctrine laws did not, on average, deter crimes including burglary, robbery and aggravated assault.

The authors note that their findings effectively negate the “possibility that castle doctrine laws cause economically meaningful deterrence effects” on general crime. Furthermore, the authors conclude that “by lowering the expected costs associated with using lethal force, castle doctrine laws induce more of it … due either to the increased use of lethal force in self-defense situations, or to the escalation of violence in otherwise nonlethal conflicts.”

Another 2012 paper, from researchers at Georgia State University, draws similar conclusions; its findings “raise serious doubts against the argument that Stand Your Ground laws make America safer.” Some statistical analysis has also found that stand your ground laws produce unequal outcomes in trial contexts, with a finding of “justifiable homicide” more likely in the case of a white-on-black killing, according to data from the Urban Institute.

Tags: crime, law, municipal, guns

    Writer: | Last updated: July 15, 2013

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    Media analysis

    Read the issue-related Time article titled "The Controversial Law at the Heart of the Trayvon Martin Case."

    1. What key insights from the news article and the study in this lesson should reporters be aware of as they cover these issues?

    Study analysis

    Read the study titled “Does Strengthening Self-Defense Law Deter Crime or Escalate Violence? Evidence from Castle Doctrine.”

    1. What are the study's key technical term(s)? Which ones need to be put into language a lay audience can understand?
    2. Do the study’s authors put the research into context and show how they are advancing the state of knowledge about the subject? If so, what did the previous research indicate?
    3. What is the study’s research method? If there are statistical results, how did the scholars arrive at them?
    4. Evaluate the study's limitations. (For example, are there weaknesses in the study's data or research design?)
    5. How could the findings be misreported or misinterpreted by a reporter? In other words, what are the difficulties in conveying the data accurately? Give an example of a faulty headline or story lead.

    Newswriting and digital reporting assignments

    1. Write a lead, headline or nut graph based on the study.
    2. Spend 60 minutes exploring the issue by accessing sources of information other than the study. Write a lead (or headline or nut graph) based on the study but informed by the new information. Does the new information significantly change what one would write based on the study alone?
    3. Compose two Twitter messages of 140 characters or fewer accurately conveying the study’s findings to a general audience. Make sure to use appropriate hashtags.
    4. Choose several key quotations from the study and show how they would be set up and used in a brief blog post.
    5. Map out the structure for a 60-second video segment about the study. What combination of study findings and visual aids could be used?
    6. Find pictures and graphics that might run with a story about the study. If appropriate, also find two related videos to embed in an online posting. Be sure to evaluate the credibility and appropriateness of any materials you would aggregate and repurpose.

    Class discussion questions

    1. What is the study’s most important finding?
    2. Would members of the public intuitively understand the study’s findings? If not, what would be the most effective way to relate them?
    3. What kinds of knowledgeable sources you would interview to report the study in context?
    4. How could the study be “localized” and shown to have community implications?
    5. How might the study be explained through the stories of representative individuals? What kinds of people might a reporter feature to make such a story about the study come alive?
    6. What sorts of stories might be generated out of secondary information or ideas discussed in the study?