Not enough evidence to say gun laws reduce violence

Feb 10 2005

Despite a proliferation of gun registration requirements, bans on specific firearms and “zero tolerance” policies for guns in schools over the past three decades, the jury is still out on whether these laws help prevent gun violence, according to a new review of studies in the American Journal of Preventive Medicine.

The review by the Task Force on Community Preventive Services concluded that there was “insufficient evidence” to determine whether any of the federal, state and local gun laws reviewed had an effect on gun-related deaths, violent crimes, suicides and other outcomes.

The report’s lead author, Dr. Robert Hahn of the federal Centers for Disease Control and Prevention, says “it is critical to note” that the review does not mean that gun laws are ineffective.

“We mean simply that we do not yet know what effects, if any, the laws have” on gun-related violence, Hahn says, and that the Task Force does not recommend that current laws be changed in any way “until effectiveness can be demonstrated one way or the other.”

Studies on the effectiveness of gun laws are plagued by poor or missing data, confusion over which laws affect which jurisdictions and underreporting of violent gun-related crimes, the task force researchers say.

In addition, says Hahn, “laws are a challenging area to research,” especially since researchers can’t control who would be “exposed” to a particular law, as they might in other types of experiments.

Hahn and colleagues reviewed studies published between 1979 and March 2001 of firearm laws and violence prevention. The studies compared rates of gun-related violence among groups of people who had lived under the laws with those who had not lived under the laws or who had little exposure to the laws.

The studies included laws to ban certain types of guns or ammunition, such as fully automatic assault weapons and the cheap handguns commonly known as “Saturday night specials.” Others studies examined laws that restrict certain people from buying guns, determine waiting periods for gun purchases, require gun registration, allow for concealed weapon and impose “zero tolerance” for firearms in schools. The task force also reviewed studies that looked at combinations of these laws.

In each case, the researchers could not find enough evidence to suggest that the laws had any effect on a variety of outcomes, from homicides to aggravated assaults to suicides.

For instance, Hahn and colleagues found that the five studies of the 1976 ban on handguns in Washington, D.C. and its effects on the city’s homicide rate were inconclusive.

Hahn says the task force found “no evidence for or against” the idea that handgun bans make it harder for residents of high-crime neighborhoods to protect themselves.

The federal Brady Law, which requires automatic background checks and a waiting period before a gun can be purchased from a dealer, was among the laws reviewed in the studies. Its effectiveness also remains uncertain, according to Hahn and colleagues.

(The Brady Campaign to Prevent Gun Violence did not respond to a request for comment.)

Despite the intense interest in guns and schools after the 1999 shootings at Columbine High School in Colorado, the researchers found no studies at all that measured” zero tolerance” laws for firearms and schools and their effects on school violence.

Hahn says future gun law studies would benefit from better records of gun-related violence and accessibility to gun ownership and sales records. Although some information on gun sales is available, it is “limited to protect the privacy of firearm owners,” Hahn says.

Gun law researchers are also hindered by “disputes about which states have which types of laws,” Hahn says, making it hard to determine which laws may affect the rates of violence for a particular population.

Gun-related injuries were the second leading cause of injury-related deaths in the United States in 2001, the last year for which complete data are available.

The Task Force is a nonfederal group first convened by the Department of Health and Human Services in 1996, with members appointed by the Director of the Centers for Disease Control and Prevention, to systematically review and make recommendations about a range of public health issues.

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