Laws do not deter crime
Two Professors from Texas A&M University, Mark Hoekstra and Cheng Cheng, studied whether the Castle Doctrine laws deter crime.
The answer, according to the Wall Street Journal, is no. In fact, the evidence suggests the laws have led to an increase in homicides.
From the study: http://econweb.tamu.edu/mhoekstra/castle_doctrine.pdf
Results indicate that the prospect of facing additional self-defense does not deter crime. Specifically, we find no evidence of deterrence effects on burglary, robbery, or aggravated assault. Moreover, our estimates are sufficiently precise as to rule out meaningful deterrence effects.
In contrast, we find significant evidence that the laws increase homicides. Suggestive but inconclusive evidence indicates that castle doctrine laws increase the narrowly defined category of justifiable homicides by private citizens by 17 to 50 percent, which translates into as many as 50 additional justifiable homicides per year nationally due to castle doctrine. More significantly, we find the laws increase murder and manslaughter by a statistically significant 7 to 9 percent, which translates into an additional 500 to 700 homicides per year nationally across the states that adopted castle doctrine.
Thus, by lowering the expected costs associated with using lethal force, castle doctrine laws induce more of it. This increase in homicides could be due either to the increased use of lethal force in self-defense situations, or to the escalation of violence in otherwise non-lethal conflicts. We suspect that self-defense situations are unlikely to explain all of the increase, as we also find that murder alone is increased by a statistically significant 6 to 11 percent.
To read more: http://blogs.wsj.com/law/2012/06/11/study-says-stand-your-ground-laws-increase-homicides/