A new study on gun laws finds that the more legislation a state has, the fewer gun deaths it experiences.
It's a timely finding, given increased political interest in gun control measures after December's mass shooting at an elementary school in Newtown, Conn. It's also a controversial one, given the strong emotions surrounding gun violence and gun control. Dave Workman, an editor at Gun Week magazine and communications director for the Citizens Committee for the Right to Keep and Bear Arms in Bellevue, Wash., provided one anti-gun law response.
"It's presumably the result they wanted to get in order to have the public believe something. Is that fair? Is that good science? Is that good research? I don't know," Workman told NBC's Vitals Blog.
The study is indeed limited, and is no slam-dunk for advocates of a particular law. But the data isn't useless either. Here's what the study can (and can't) tell us.
Gun study basics
The research, which is freely available online in the journal JAMA Internal Medicine, was conducted by Dr. Eric Fleegler, a physician in pediatric emergency medicine at Boston Children's Hospital, and colleagues. The researchers had been studying the impact of child booster-seat laws on pediatric car accident deaths (the laws decreased them), when teenager Trayvon Martin was shot in Florida in 2012, touching off a national firestorm about firearms and "Stand Your Ground" laws.
"The question raised among us was, what roles do laws play in deaths like this?" Fleegler told LiveScience. [5 Milestones in Gun Control History]
To find out, the researchers turned to publicly available data on gun deaths from the Centers for Disease Control and Prevention (CDC) for 2007 to 2010, the most recent year data are available.
They also used information on state laws from the Brady Center to Prevent Gun Violence. The Center keeps a database of gun control and gun safety laws in every state. There are five categories of law: anti-trafficking laws, background check laws, child safety laws, such as those requiring safe storage of guns, bans of military-style assault weapons and laws banning weapons in public places. In total, there were 28 possible laws states could enact, Fleegler found.
Comparing the effect of a single law is difficult, because legislation rarely comes alone, Fleegler said.
"Many states don't have any laws in a particular category, and the states that have those laws often have other ones," he said.
So the researchers devised a "one point for one law" legislation strength score that rated states on gun control from a scale of zero to 28. Utah scored lowest, with zero, while Massachusetts scored highest, with 24.
Guns and deaths
The rates of firearm deaths in each state were similarly wide-ranging. Between 2007 and 2010, there were 121,084 firearms fatalities from suicide and homicide in the United States (the researchers excluded accidental shootings). Of these, 73,702 were suicides and 47,382 were homicides. [The 10 Most Destructive Human Behaviors]
Louisiana had the highest gun-death rate, at 17.9 per 100,000 residents. Hawaii had the lowest, at 2.9 gun deaths per 100,000.
And gun laws and gun deaths were related. The states in the top 25 percent of gun legislation strength had a 42 percent reduction in gun deaths compared with the states in the bottom 25 percent. That number included a 40 percent drop in homicides and a 37 percent drop in suicides.
In absolute terms, the states with the strongest laws had 6.64 fewer deaths per 100,000 residents than the states with the weakest.
Notably, when gun violence was lower, other types of violence did not go up, suggesting people without guns do not kill themselves or others by other means, Fleegler said. In the case of suicide, Fleegler said, studies show that few people who fail at their first suicide attempt will successfully kill themselves later. But if the first attempt involves firearms, it has about an 85 percent likelihood of being lethal. If it involves other means, that rate is about 2 percent.
The analyses took into account state demographics, including population density, firearm ownership, non-firearm violent deaths, and education, poverty, age, sex, race and unemployment of the population.
What it all means
But the study can't prove that the gun laws cause the lower rates of gun violence, as Fleegler is quick to point out. Here's what the researchers do know: States with more gun laws have lower rates of household gun ownership as well as lower rates of gun violence. States with the most laws have gun ownership rates of around 20 percent, while states with the least have rates as high as 70 percent. [Private Gun Ownership in the US (Infographic)]
The relationship could be causal. Perhaps gun laws discourage gun ownership, which in turn discourages violence. (Many studies have found that higher gun ownership is linked to more gun deaths.)
Or perhaps states where gun ownership isn't so popular find it easier to pass gun laws, meaning it's the culture rather than the laws that leads fewer people to buy guns.
Effects of a research freeze
Nor could the study take into account factors like local enforcement of gun laws, loopholes in laws, or guns moving across state borders. The limitations frustrated Dr. Garen Wintemute, a physician in emergency medicine at the University of California, Davis, who wrote a commentary accompanying the article.
"Here, there can be no recommendation at all," Wintemute wrote. But he doesn't blame Fleegler and his colleagues, who did the research without any funding. The researchers "did well with the data available to them," but were limited by the years-long freeze in gun violence research enacted by Congress in the 1990s, which forbids the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH) from funding research that could be used to promote gun control.
After Newtown, President Barack Obama ordered those agencies to start funding such research again. Fleegler said he's not aware of any changes yet at either agency, though the National Institute of Justice has solicited research proposals with plans to fund three projects. Congress ultimately controls the purse strings of the CDC and NIH, and it isn't yet clear whether research funding will start again.
The result, Wintemute wrote, is that no more than a dozen American researchers have focused their careers on firearm violence.
"This is not how the United States usually responds to a public health emergency," he wrote.
Fleegler sees the same need for research that reaches beyond what he and his colleagues were able to do.
"There's important data that needs to be collected about what happens in a smaller microcosm," he said. "What is going on in terms of enforcement of laws? What happens in terms of law and mortality rates more at the city level than at the state level?"
With an estimated 300 million guns in circulation in the United States, new laws won't show effects immediately, Fleegler said.
"This type of research both needs to be done very thoughtfully, and it will take time," he said.
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Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.