Do states with stricter gun laws have less gun violence than those with few restrictions?
Researchers who have studied the issue argue they generally do, but with some caveats. They cannot say whether the laws, or some other factors, are the reason for a lower rate of firearm deaths and that there are exceptions.
President Barack Obama addressed the matter in a news conference hours after a gunman killed eight students and a teacher at an Oregon community college.
"We know that states with the most gun laws tend to have the fewest gun deaths," Obama said.
David Hemenway, director of the Harvard Injury Control Research Center, said Obama's claim was accurate and supported by many studies. The likely reason is that states with stronger gun laws have fewer guns and fewer suicides and homicides from them, he said.
The White House says Obama based his claim on a report published in August by the National Journal, which found that states with the fewest gun-related deaths — including homicides, suicides and accidents — had stricter laws than those with the highest number. The study looked at laws such as those that require permits to purchase handguns and universal background checks on sales.
A study published in 2013 in the Journal of the American Medical Association compared firearm deaths in states to the number of restrictive gun laws each state had out of 28 tracked by the Brady Center to Prevent Gun Violence.
Looking at 120,000 deaths over a four-year period, researchers concluded that a "higher number of firearm laws in a state are associated with a lower rate of firearm fatalities in the state, overall and for suicides and homicides individually." They acknowledged exceptions, with some states featuring loose restrictions but low rates of gun deaths. They also cautioned against drawing a cause-and-effect relationship, saying more research was needed.
Because such studies also consider suicides in calculating firearm deaths, critics say it is misleading to cite them when arguing for ways to prevent mass shootings. Suicides account for the majority of America's roughly 30,000 annual gun deaths.
Catherine Mortensen, a spokeswoman for the National Rifle Association, said studies that have found links between states' gun laws and firearm deaths fail to consider all the relevant factors that might influence fatality rates, such as how much money is spent in each state on policing and suicide-prevention. She said the 2013 study published in the medical association journal contained a scoring system for laws that was "subjective and not verified by an independent source."
Authors conceded their scoring system "has not been validated." But the lead author, Eric Fleegler of Boston Children's Hospital, said he believed the evidence was clear that the risk of dying from suicide and homicide is generally reduced in states with the most gun restrictions.
"In states where there has been more legislation related to firearms purchasing and the way guns are stored and carried, there are lower rates of fatalities," he said. "This is important."