John Lott, an economist who lives in Virginia, says he and his wife once didn’t allow even toy guns in their home.
That was before he researched how crime rates are affected by laws allowing concealed weapons. Now, Lott says, he owns several firearms.
Lott says crime goes down by as much as 5 percent over time when the government allows citizens to carry concealed firearms. The reason, he says, is simple: Robbers and rapists and other thugs don’t like getting shot.
“You make it more costly and riskier for criminals to do something, it’s less likely that they’ll do it,” says Lott, who has written a book on his findings and also testified before Congress and several state legislatures.
Not necessarily, responds John Donohue III, a Yale University law professor and economist who has countered Lott’s findings with research of his own. Donohue says his data shows that laws allowing concealed weapons have, at best, no influence on the crime rate and may lead to increases in aggravated assaults.
“My general sense is, the best we can say today with the most recent data is that the impact of these right-to-carry laws is not great,” Donohue says. “But what effect there is seems to be harmful. … I probably published two or three articles in the last year that showed the reduction of 3 or 4 percent is completely wrong.”
How can two researchers with access to the same data reach such opposite conclusions?
Lott questions Donohue’s methodology. Donohue says data from the 1980s and early 1990s that Lott used in the first edition of his book have proven flawed, and it is can be difficult to admit mistakes.
“The problem is, once you’ve written a book called ‘More Guns Less Crime,’ it’s very hard to back away and say, ‘Oops, I got it wrong,’” Donohue said. “No one ever asked me to testify (before lawmakers). And I think there’s a reason for that. Everybody wants an advocate. I want to figure out what’s true.”
Many variables in play
Figuring out whether concealed firearms reduce crime is a lot more complicated than perusing FBI statistics on crime.
Otherwise, it would be simple to cite Vermont, which allows gun owners to pack concealed firearms without any permits, as proof that hidden guns deter crime. Vermont, with 136 cases of violent crime per 100,000 residents in 2008, has one of the lowest violent-crime rates in the nation.

In Michigan, which issued nearly 66,500 concealed-gun permits in the year ending last June, police also say they haven’t noticed any change in crime that can be linked to concealed weapons since the state began issuing permits in 2001.However, they also say they haven’t noticed a downside.