Homicide rates increase in states with ‘stand your ground’ laws, research finds
The death of Florida teen Trayvon Martin in February spurred a national debate about the so-called “stand your ground” law or “castle doctrine,” which expands grounds for the justifiable use of deadly force in self-defense.
In a recent Texas A&M University study, Mark Hoekstra, an associate professor in the Department of Economics, and Cheng Cheng, a doctoral student in the department, made two significant observations: while stronger self-defense laws did not deter burglary, robbery, or aggravated assault, in states with stand your ground laws, homicide rates increased by seven to nine percent (or 500 to 700 more homicides per year across 23 states).
In 2005, Florida became the first state to legally expand self-defense protections by removing the duty to retreat before using lethal force outside one’s own home, as well as by adding other provisions that address civil liability and a “presumption of reasonable fear” when acting in self-defense. Twenty-two other states have passed similar laws, though some are more restrictive than others.
The term “castle doctrine” comes from the English common law principle that people have no duty to retreat before using lethal force in self-defense when in their own home, or castle. The purpose of the laws is to help victims better protect themselves against violent crime.
For their study, Hoekstra and Cheng analyzed state-level crime data from 2000 to 2009 from FBI Uniform Crime Reports. They began their initial investigation last summer, well before the Trayvon Martin case pushed self-defense laws into the spotlight.
To the untrained eye, their research doesn’t fall into a category of traditional economics, but Hoekstra says it is all about incentives.
“When you change self-defense law, you change incentives. You change the incentives of people protecting themselves – now it’s lower cost to use lethal force, for example, after a state passes a castle doctrine law,” Hoekstra said. “So on the one hand you might expect to get more lethal force because you lowered the cost and on the other hand you might expect to get less crime because you raised the expected cost to criminals.”
But as Hoekstra found, the results indicated only that there was an increase in the use of lethal force. The main question now, Hoekstra says, is why homicides increased.
“I think there are several reasonable explanations for why homicides would go up, but I’m not sure which one is true,” he said. “It could be that the increase in homicides is driven by an increase in self-defense killings. On the other hand, it could be that the increase in homicides is due to an escalation of violence in otherwise nonviolent situations.”
Hoekstra and Cheng plan to investigate the nature of the data in the future. They aim to contact the states directly to learn more about the homicide victims and whether or not they have criminal backgrounds. But they don’t know whether or not all of the data they need will be available.
The authors predict that their findings will have significant policy implications. They conclude their report by stating that “an informed debate over these laws will weigh the increased protection offered to law-abiding citizens against the increase in homicide that results from the laws.”