New Stanford research confirms that right-to-carry gun laws are linked to an increase in violent crime.
Right-to-carry or concealed-carry laws have generated much debate in the past two decades – do they make society safer or more dangerous?
While there is no federal law on concealed-carry permits, all 50 states have passed laws allowing citizens to carry certain concealed firearms in public, either without a permit or after obtaining a permit from local government or law enforcement.
Recently published scholarship updates the empirical evidence on this issue. Stanford law Professor John J. Donohue III, Stanford law student Abhay Aneja and doctoral student Alexandria Zhang from Johns Hopkins University were the co-authors of the study.
"Trying to estimate the impact of right-to-carry laws has been a vexing task over the last two decades," said Donohue, the C. Wendell and Edith M. Carlsmith Professor of Law, in an interview.
He explained that prior research based on data through 1992 indicated that the laws decreased violent crime. But in 2004, he noted, the National Research Council issued a report that found that even extending this data through 2000 revealed no credible statistical evidence these particular laws reduced crime.
'Totality of the evidence'
Now, Donohue and his colleagues have shown that extending the data yet another decade (1999-2010) provides the most convincing evidence to date that right-to-carry laws are associated with an increase in violent crime.
"The totality of the evidence based on educated judgments about the best statistical models suggests that right-to-carry laws are associated with substantially higher rates" of aggravated assault, rape, robbery and murder, said Donohue.
The strongest evidence was for aggravated assault, with data suggesting that right-to-carry (RTC) laws increase this crime by an estimated 8 percent – and this may actually be understated, according to the researchers.
"Our analysis of the year-by-year impact of RTC laws also suggests that RTC laws increase aggravated assaults," they wrote.
The evidence is less strong on rape and robbery, Donohue noted. The data from 1979 to 2010 provide evidence that the laws are associated with an increase in rape and robbery.
The murder rate increased in the states with existing right-to-carry laws for the period 1999-2010 when the "confounding influence" of the crack cocaine epidemic is controlled for. The study found that homicides increased in eight states that adopted right-to-carry laws during 1999-2010.
Research obstacles, next step
"Different statistical models can yield different estimated effects, and our ability to ascertain the best model is imperfect," Donohue said, describing this as the most surprising aspect of the study.
He said that many scholars struggle with the issue of methodology in researching the effects of right-to-carry laws. But overall, his study benefits from the recent data.
Donohue suggested it is worth exploring other methodological approaches as well. "Sensitive results and anomalies – such as the occasional estimates that right-to-carry laws lead to higher rates of property crime – have plagued this inquiry for over a decade," he said.
Explore further: Restrictive concealed weapons laws can lead to an increase in gun-related murders
Aneja, Abhay and Donohue, John J. and Zhang, Alexandria, "The Impact of Right to Carry Laws and the NRC Report: The Latest Lessons for the Empirical Evaluation of Law and Policy (September 4, 2014)." Stanford Law and Economics Olin Working Paper No. 461. Available at SSRN: ssrn.com/abstract=2443681 or dx.doi.org/10.2139/ssrn.2443681