There's nothing simple about gun control, a tangle of legal, political and public-health issues complicated by cultural preferences and regional biases. Passions run high on all sides. Lifelong hunters who grew up with firearms, urban victims of gun violence, Second Amendment scholars, NRA lobbyists, chiefs of police—they've all got cases to make and they make them well, often contentiously.

For the past 15 years, much of the debate has centered on the effectiveness of the Brady Handgun Violence Prevention Act, the federal gun-control bill that was passed in 1993. Critics say the focus on law-abiding gun buyers doesn't address the real issue—bad guys who acquire their weapons illegally. Supporters say that the bill stops thousands of illegal gun purchases and deters crime and violence. Now medical research has come to the rescue, sifting through the data to figure out which legal measures work best to reduce firearm suicides and homicides.

In a paper published in the May issue of the American Journal of Preventive Medicine, Steven Sumner, a third-year med student (who conceived the project), and Dr. Peter Layde, codirector of the Injury Research Center at the Medical College of Wisconsin, found that local background checks, which are optional and used by just a handful of states, were more effective than the federal background checks mandated by the Brady law. The report, which has the elegant simplicity of the best research, compared the homicide and suicide rates in states that perform only federal checks with states that do state-level checks and those that perform local-level checks. The local-level checks were associated with a 27 percent lower firearm suicide rate and a 22 percent lower homicide rate among adults 21 and older, the legal age to purchase a gun. (The state checks also reduced gun violence, but by much less.)

Why are local checks so much better? "We hypothesize that it's due to access to additional information that's not available at the federal checks," says Layde, "particularly related to mental-health issues and domestic-violence issues." All 50 states use the National Instant Criminal Background Check System (NICS), the minimum required under Brady, while 17 states also perform state-level checks and 12 do additional local-level checks. Layde says the NICS databases are "very complete" when it comes to tracking fugitives from justice, felony indictments and convictions, dishonorable discharges and some other factors that disqualify a person from purchasing a firearm. However, it appears that a lot of critical data gathered at the local level, involving things like restraining orders and commitments to mental institutions, are not filtering up to the federal level.

"This is the first study that's looked at this issue," says Layde. "If the magnitude of impact we found were in fact to apply to all 50 states, you would expect a very substantial reduction in suicides and homicides linked to firearms, many thousands." However, background checks can be both an administrative and a cost burden for strapped and stretched local authorities. There is another way to get the same results: improve the flow of local information to the NICS databases. "In an ideal world," says Layde, "you might not have to have the local agencies involved if you just reliably got all the data they had up to the federal level."

As for wading into the middle of one of the country's most controversial issues, Layde is unfazed. "I think our role in this area is to try to provide objective information that policymakers can use to form the best relevant policies," he says. "Having that objectivity and trying to do a clear, clean scientific approach is far more valuable than me getting up on a soapbox and espousing my personal views, which I keep to myself." Spoken like a true scientist.

© 2008