Debate on stand your ground laws

Gun Owners of America support the controversial laws and a professor responds



Alex Halperin
January 9, 2013 10:15PM (UTC)

Erich Pratt, Gun Owners of America

Castle Doctrine laws have been instrumental in protecting the rights of citizens to defend their homes and families -- especially in the face of many prosecutors who, in years past, felt that citizens should rely on 9-1-1 or flee their homes when attacked.


Now there is a study by Cheng Cheng and Mark Hoekstra which alleges that Castle Doctrine laws are escalating violence. But the fact is the Cheng-Hoekstra study actually shows a drop in burglary, robbery and aggravated assault -- although, because of their bias, the authors dismiss this as insignificant and only helpful to those who are “legally justified in protecting themselves in self-defense.” Of course, any deterrent effect at all is precisely what one would expect to happen from a state’s enacting Castle Doctrine laws.

The researchers, after conceding this, embarked upon a red herring analysis of the homicide rates. Even though homicide rates would NOT seem to be connected to the passage of Castle Doctrine laws in a state in any significant way, the biased researchers conclude that “castle doctrine increases homicide.” But how exactly does giving people greater legal protections in defending their homes result in more homicides? The authors offer speculations, but no hard evidence that homeowners are misapplying these laws and killing intruders outside the legal protections of Castle Doctrine law.

Interestingly, the tables in the study show that in the 18 states which have adopted Castle Doctrine laws (in 2007 or before), they all experienced a spike in their murder rates from 2006-2007, but then also enjoyed a precipitous drop the following year.

So, here’s a question for Cheng and Hoekstra: If the Castle Doctrine laws are to blame for the initial spike in homicide, then shouldn’t they also get the credit for the ensuing drop in homicide? Or maybe, as suggested above, Castle Doctrine laws really don’t impact homicide murder rates that much -- one way or another.

By the way, the study cuts off at 2010. But here’s a spoiler alert: According to FBI statistics, the national homicide rate dropped another two percent from 2010 to 2011. This means that the homicide drop will continue to erase the supposed “jump in homicide” that Cheng and Hoekstra attribute to Castle Doctrine laws.

In closing, it should be noted that during the first decade of this century, 40 million new guns were manufactured for sale inside the U.S., even while the murder rate has dropped 14%.(1)


It seems that more guns have resulted in less crime.

Mark Hoekstra, Texas A&M University

1. As our paper makes clear, we are examining the effect of laws that extend castle doctrine outside the home, and which in most cases also establish a presumption of reasonable fear and remove civil liability for those justified under criminal law. The name “castle doctrine law” comes from the fact that under English common law, and thus typically in either state statute or case law, there was not a duty to retreat when inside one’s own home. These laws put that explicitly into statute, and more importantly extend “castle doctrine” to places outside the home and add other protections. Thus, these laws lower the legal threshold required for the justifiable use of lethal force. Empirically we find that this results in additional homicides.

2. We estimate the effect of the laws by comparing the change in homicide rates experienced by states after adopting the laws to the changes in homicide rates. That is, we use non-adopting states as a control group; the changes they experience over time form our best estimate as to what would have happened to adopting states had they not passed the laws.

The data, which are publicly available from the FBI, indicate that homicide rates rose in adopting states relative to non-adopting states after the passage of the laws. This can be seen in Figure 1 of our paper. That set of figures shows the natural log of homicide rates, which means differences and changes can be easily interpreted in terms of percent. A large part of this relative increase is driven by an absolute increase in homicide rates after adoption, and part of it is driven by the fact that the declines in 2009 and 2010 were smaller in adopting states than in non-adopting states.


To be clear, this is different than a time-series approach, which would compare only how homicide rates changed over time within adopting states, ignoring what happened elsewhere. We plan to eventually make available a description of our methods, along with simple examples, on my website, for interested parties like Mr. Pratt and readers. But for now, the direct response to Mr. Pratt is that we would not attribute a drop in crime rates over time in adopting states to these laws if other states, including other states in the same region, experienced similar or larger drops in those same crime rates.

The comment about 2011 crime rates parallels a similar criticism we received from someone when our sample went through 2009 (we started the project when 2010 data were not yet released). The claim was that adding 2010 data would undo the result, and that we deliberately left out 2010 data due to our supposed sinister motives. And it is true that homicide rates in most states fell from 2009 to 2010 (again, see Figure 1 for aggregate numbers). Of course, as readers of the current draft know, it turns out that including the 2010 data didn’t change the finding. That’s because adopting states experienced similar or even smaller drops in homicide rates compared to non-adopting states.

Of course, adding 2009 and 2010 data would affect one’s estimates if one were simply comparing pre-law crime rates to post-law crime rates. But we would not advocate that; many factors change over time—especially several years of time—and one needs to account for that. We do so by comparing changes within adopting states to changes within non-adopting states over the same time period.


3. Our study does not show any evidence that robbery, burglary, or aggravated assault rates fell due to these laws. I don’t know where that assertion came from, but it is not true. Estimates are positive, small, and statistically indistinguishable from zero.

4. To clarify with respect to the graph of 2006 adopters (see Figure 1b): Our estimates come from comparing the average change from the entire pre-law period to the entire post-law period across the two groups of states. Our estimate is not, for example, only considering the initial absolute increase in homicide rates experienced by the 2006 adopters. (Of course, we are not only considering 2006 adopters in the reported estimates; that should go without saying.)

Alex Halperin

Alex Halperin is news editor at Salon. You can follow him on Twitter @alexhalperin.

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