More guns, more crime: Stanford research undermines the NRA's favorite study

Researchers at Stanford have concluded that, contrary to the political commonplace that right-to-carry (RTC) or concealed-carry laws decrease violent crime, such laws have actually increased the number of violent crimes in the states that have passed them since 1999.

Law professor John J. Donohue III said that "[t]rying to estimate the impact of right-to-carry laws has been a vexing task over the last two decades," in large part because the most frequently cited study, John Lott and David Mustard's "More Guns, Less Crime" (1997), ended "just before the extraordinary crime drop of the 1990s."

Despite its problems, Lott and Mustard's study is regularly mentioned in public policy debates by pro-gun advocates and the National Rifle Association. As Donohue notes, "even as the empirical support for the Lott and Mustard thesis was weakening, its political impact was growing [as] legislators continued to cite this work in support of their votes on behalf of RTC laws."

"The 'More Guns, Less Crime' claim," he added, "has been invoked often in support of ensuring a personal right to have handguns under the Second Amendment."

Donohue and his assistants, Stanford law student Abhay Aneja and Johns Hopkins doctoral student Alexandria Zhang, contend that a more accurate estimate of the effect of RTC laws on violent crime would examine data from 1999-2010, because that "period does include the immense increases and then declines associated with the rise and fall of the crack epidemic."

When the "confounding influence" of the crack cocaine epidemic is accounted for, the trio found that "[t]he 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 murder, rape, robbery and aggravated assault.

The strongest evidence was for aggravated assault, which increased by almost 8 percent, but homicides also increased in the eight states that adopted RTC laws between 1999 and 2010.

Read "The Impact of Right to Carry Laws and the NRC Report: The Latest Lessons for the Empirical Evaluation of Law and Policy" here.