THE BURNED OVER DISTRICT

Apparently when you repeal laws applying to guns that were designed to maintain public safety the result is a decline in public safety. Now who could have imagined that! Certainly not the folks in Missouri who had to see for themselves.

In the past decade, Missouri has been a natural experiment in what happens when a state relaxes its gun control laws. For decades, it had one of the nation’s strongest measures to keep guns from dangerous people: a requirement that all handgun buyers get a gun permit by undergoing a background check in person at a sheriff’s office.

But the legislature repealed that in 2007 and approved a flurry of other changes, including, last year, lowering the legal age to carry a concealed gun to 19. What has followed may help answer a central question of the gun control debate: Does allowing people to more easily obtain guns make society safer or more dangerous?

It is difficult to isolate the impact of gun laws in a single state, given the pervasiveness of interstate trafficking and illegal markets, but a variety of measures, including a marked increase in police seizures of guns bought in-state, suggest the changes in Missouri’s laws have had some effect.

Research by Daniel Webster, the director of the Johns Hopkins Center for Gun Policy and Research, found that in the first six years after the state repealed the requirement for comprehensive background checks and purchase permits, the gun homicide rate rose by 16 percent, compared with the six years before. In contrast, the national rate declined by 11 percent over the same period. After Professor Webster controlled for poverty and other factors that could influence the homicide rate, and took into account homicide rates in other states, the result was slightly higher, rising by 18 percent in Missouri.

New federal death data released this month for 2014 showed a continuation of the trend, he said. Before the repeal, from 1999 to 2006, Missouri’s gun homicide rate was 13.8 percent higher than the national rate. After, from 2008 to 2014, it was 47 percent higher. (The new data also showed that the national death rate from guns is now equal to that of motor vehicle crashes for the first time since the government began systematically tracking it.)

Other measures suggested that criminals had easier access to guns after the permit law was repealed. Professor Webster analyzed data from the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, and found that the share of guns that were linked to crimes soon after they were bought doubled in the state from 2006 to 2010. The portion of guns confiscated by the police in Missouri that had been originally bought in the state — ordinarily a very stable statistic — rose to 74 percent last year, from 56 percent before the law changed...

“There is this idea that law-abiding citizens’ rights are being secured,” said Richard Rosenfeld, a professor of criminology at the University of Missouri, St. Louis. “In fact, it’s the people most inclined to do harm whose privileges are being secured.”

Their privileges are secured because they are the ones most likely to buy a gun, which is the only reason some are so eager to remove public safety laws.