Stand Your Ground laws and homicides

by Andrew Gelman on June 27, 2012 · 6 comments

in Judicial,Law

Jeff points me to a paper by Chandler McClellan and Erdal Tekin which begins as follows:

The controversies surrounding Stand Your Ground laws have recently captured the nation’s attention. Since 2005, eighteen states have passed laws extending the right to self-defense with no duty to retreat to any place a person has a legal right to be, and several additional states are debating the adoption of similar legislation. Despite the implications that these laws may have for public safety, there has been little empirical investigation of their impact on crime and victimization. In this paper, we use monthly data from the U.S. Vital Statistics to examine how Stand Your Ground laws affect homicides. We identify the impact of these laws by exploiting variation in the effective date of these laws across states. Our results indicate that Stand Your Ground laws are associated with a significant increase in the number of homicides among whites, especially white males.According to our estimates, between 4.4 and 7.4 additional white males are killed each month as a result of these laws.We find no evidence to suggest that these laws increase homicides among blacks. Our results are robust to a number of specifications and unlikely to be driven entirely by the killings of assailants. Taken together, our findings
raise serious doubts against the argument that Stand Your Ground laws make America safer.

I don’t really trust their regressions. I mean, sure, 5 additional homicides per month is as good an estimate as any, but the conclusions are coming from the data, which McClellan and Tekin display reasonably well:

I think one would want to understand these wavy ups and downs in the curves before making any definitive pronouncements.

From a policy standpoint, I guess it’s no surprise that Stand Your Ground laws could be associated with an increase in homicide. After all, these laws aren’t really enacted as a homicide-control measure, right? It’s more the opposite, that they legalize certain violence that used to be criminal. I could imagine Stand Your Ground decreasing homicide in some sort of deterrence effect, but that would seem to me to be a bit of a bank-shot of an effect, hoping that legalizing some acts of violence would decrease others. It’s possible but I wouldn’t bet on it. To put it another way, even if Stand Your Ground laws really did increase homicides, I could imagine people still supporting the laws on the grounds that some of these homicides were justifiable. I suppose that would be the next stage of research but it would take a lot more effort as it would have to investigate the story of each homicide.

{ 6 comments }

Robert June 28, 2012 at 5:10 am

Looks like seasonality. Here’s the distribution of when the SYG laws took effect:
jan 0, feb 0, mar 1, apr 2, may 1, jun 2, jul 8, aug 4, sep 4, oct 2, nov 2, dec 0.
In addition, the states with SYG laws aren’t evenly geographically distributed across the US.

Robert June 28, 2012 at 5:38 am

Just to clarify, I would have seasonally-adjusted the mortality rates, maybe with something like a STL, then done it separately for each sex. My guesses are that there’s less seasonality and less effect (if any) of SYG on female gunshot homicide than male gunshot homicide but the data might be able to tell us that. If so, then I’d yank out the women, focus only on the men, and do a comparison of before and after SYG passage against seasonally-adjusted rates. But that’s just off the top of my head.

jay June 29, 2012 at 11:14 am

for many states, the laws merely codified in statute what had been case law for hundreds of years. did they address that?

Robert July 1, 2012 at 2:19 am

Which states are those?

Mike July 3, 2012 at 3:41 pm

What’s more striking in these data than the pre-/post-comparison is the sharp contrast between SYG and non-SYG states. Could it be that the SYG states are more inclined to pass such laws because they’re inured to a relatively high level of violence already?

willford July 7, 2012 at 6:23 am

I guess people should not defend themselves?? If it is justifiable homicide W.G.A.S.

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