Darren Wilson, George Zimmerman, and Justifiable Homicide (and Stand Your Ground Laws)

The refusal of a grand jury to indict Darren Wilson for killing Michael Brown in Ferguson, Missouri has led to comparisons with the acquittal of George Zimmerman in the killing of Trayvon Martin (e.g., Inquisitr and Think Progress).

Of course, the cases are different in that Wilson was a sworn law enforcement officer acting in the line of duty, while Zimmerman was a private citizen with a concealed weapon permit. But both used lethal force in self-defense and both were found to have committed justifiable homicide.

Image courtesy of USNWR.com
Image courtesy of USNWR.com

The non-indictment of Darren Wilson — and since then, of New York police officer Daniel Pantaleo in the strangulation death of Eric Garner in Staten Island, not to mention the shooting of Tamir Rice by Cleveland officer Timothy Loehmann — has brought the issue of police justifiable homicide into the spotlight. But before Wilson and Pantaleo and Loehmann, interest in justifiable homicide had already grown dramatically due to the Trayvon Martin shooting.

Especially in relation to “Stand Your Ground” laws, interest in justifiable homicide was evident at the recent meetings of the American Society of Criminology, held in San Francisco in late November.

There were two panels devoted to the topic of justifiable homicide and Stand Your Ground laws, both organized by sociologist Jennifer Dawn Carlson (a terrific scholar, about whom I have written previously). Of particular interest to many is whether there is a causal relationship between the rise of Stand Your Ground laws and a rise in justifiable homicides.

Carlson herself presented a most fascinating table on the number of police versus civilian justifiable homicides in the United States in recent history. I do not have the exact table she presented, but I created my own figure representing police and civilian justifiable homicides between 1976 and 2012, using data from Supplementary Homicide Reports (part of the FBI’s Uniform Crime Reports). (To see an officially published version covering 1980 to 2008, see Figure 51 in  the Bureau of Justice Statistics report, “Homicide Trends in the United States, 1980-2008”.)

Police and Civilian Justifiable Homicide

What jumps out at me in this figure is that the trends in police and private citizen justifiable homicides vary almost directly with one another. They rise together in the late 1970s, fall together in the early 1980s, rise again to the mid-1990s, fall in the late 1990s, and stagger their way upward again to the present.

In fact, looking at these numbers not by year but as a scatterplot visually demonstrates how police and private citizen justifiable homicide vary together quite closely.

Scatterplot of Police and Citizen Justifiable Homicides
For those who are more numerically than visually oriented, the Pearson product-moment correlation coefficient (a.k.a. “Pearson’s r”) for these numbers is 0.56 (p<0.001), a quite strong correlation for social scientific data.

One conclusion I draw from these figures is that the rise of Stand Your Ground laws beginning with Florida in 2005 cannot account for the recent rise in the number of private citizen justifiable homicides, because the most recent upward trend began in 2000.

Similarly, the wave of shall-issue concealed carry laws that swept over the country beginning in Florida in 1987 cannot account for the post-2000 rise in private citizen justifiable homicides, unless it can also explain the precipitous decline in private citizen justifiable homicides between 1994 and 2000.

Indeed, neither concealed carry nor Stand Your Ground laws can be causally explanatory factors for private citizen justifiable homicides unless those same laws can also explain the rise (and fall) of police justifiable homicides, which vary almost directly with private citizen justifiable homicides. Whatever is “causing” the rise and fall of one is likely to be the source of the other.

A more fruitful line of investigation, therefore, would focus not on laws that apply only to private citizens, but on factors that can explain both police and private citizen justifiable homicides. Explaining one requires explaining the other.

(NOTE: Many have raised the concern that FBI UCR numbers dramatically underreport the number of police justifiable homicides. See the Wall Street Journal here and here, Fatal Encounters, Gun Violence Archive, Deadspin, and others. Although this is a valid concern, my argument here has to do with the trends not the absolute numbers. Assuming that the underreporting of police justifiable homicides is relatively stable over time – a safe assumption in my view – the basic argument of this blog post is unchanged.)


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