If a safety measure eliminated all but a handful of the nation's traffic fatalities per year, it would likely get an enthusiastic hearing in legislatures. If three steps could reliably prevent 9 in 10 of the deaths caused each year by the flu, public health officials would probably lobby hard for their implementation.
With a similar objective in mind, researchers at Boston University have identified specific state laws that, if implemented across the nation, might dramatically reduce the death toll from gun violence, which in many years kills about as many Americans as traffic accidents or the flu.
After comparing states' trends in firearms-related deaths against those states' decisions to adopt any of 25 gun-control measures, the researchers singled out three initiatives that were associated with robust declines in suicides, homicides and fatal accidental shootings.
The three measures linked to substantial drops in firearms-related deaths were: universal background checks for firearms sales, background checks on those buying ammunition, and a requirement that gun owners get their firearms microchipped or "fingerprinted" for identification purposes.
If all three laws were in force across the land, the number of gun deaths in the United States — 31,672 in 2010 — might decline by as much as 90%, according to their report published Thursday in the British medical journal Lancet.
Not all of the gun laws on states' books appeared to be effective. Indeed, of the 25 laws examined, nine initiatives — some of them dear to the hearts of gun-control advocates — were associated with increases in gun deaths. These included bans or restrictions on assault weapons, limits on the number of firearms a customer could purchase, and laws requiring locking devices on firearms available for sale.
Increased gun deaths were also linked to some of the measures beloved by gun-rights advocates. Those included "stand-your-ground" laws, which protect from prosecution those who use a gun to defend their home or property, and laws that give police departments discretion in granting concealed-carry permits.
Study leader Bindu Kalesan, a quantitative social researcher at Boston University, said the effort was the first to rigorously examine the impact of specific gun laws on gun-related deaths across the United States.
The researchers made adjustments for factors already known to influence gun-related deaths, such as the rates of gun ownership and of unemployment in each state (where either increases, gun deaths do too).
"The findings suggest that very few of the existing state gun-control laws actually reduce gun deaths," Kalesan said.
For public health officials intent on reducing gun deaths, she added, the results highlight "the importance of focusing on relevant and effective gun legislation."
Other researchers cautioned that establishing a link between the adoption of a gun-control measure and the subsequent trends in gun deaths falls far short of showing that the law was responsible for the observed effect.
Differing trends in states' demographics, economic circumstances and even their hospitals' ability to treat gunshot wounds may drive changes in gun death rates, for instance. And enforcement factors — most notably how quickly and completely a new law is implemented — can intervene to make it effective, toothless or even counterproductive, said Dr. Garen Wintemute, an emergency physician who studies violence prevention at UC Davis.
"I'm generally skeptical of cross-sectional studies of association," Wintemute said. "Evidence from such studies is not considered to be strong."
None of the "big three" measures identified in the new research is widely implemented in the U.S. Universal background checks for the purchase of all firearms are in force in California and Rhode Island, while Connecticut, Hawaii, Maryland, New Jersey and Pennsylvania require background checks for the purchase of all handguns.
Only Illinois, Massachusetts and New Jersey require purchasers of ammunition to have a permit to do so.
The requirement for registries that identify the ballistic fingerprint of every newly sold gun exists only in Maryland and New York. California has adopted such a measure, but its implementation has been stalled by legal challenges, Wintemute said. If California hadn't been included in this part of the analysis, the association with fewer gun deaths might not hold up and the overall reduction in gun deaths might well be lower than 90%.