Study: States with more gun laws have less gun violence

States with more gun laws have fewer gun-related deaths, according to a new study released Wednesday by Boston Children's Hospital.

The leader investigator behind the research hopes the findings will drive legislators to pass gun reform across the country and increase federal funding to research on gun laws and violence. However, at least one critic argues that the study fails to take into account several important factors such as the types of laws, enforcement of laws, and gun ownership rates in states.

"Our research gives clear evidence that laws have a role in preventing firearms deaths," said Eric Fleegler, the study's lead investigator and a pediatric emergency doctor at Boston Children's Hospital. "Legislators should take that into consideration."

Fleegler and researchers from Boston Children's Hospital, Harvard Medical School and Harvard School of Public Health studied information from all 50 states between 2007 to 2010, analyzing all firearm-related deaths reported to the Centers for Disease Control and Prevention and data on firearm laws compiled by the Brady Center to Prevent Gun Violence.

States with the most laws had a mortality rate 42% lower than those states with the fewest laws, they found. The strong law states' firearm-related homicide rate was also 40% lower and their firearm-related suicide rate was 37% lower.

Specifically, Fleeger pointed to states with many gun laws like Massachusetts, which had 3.4 gun-related deaths per 100,000 people, and New Jersey, which had 4.9 gun-deaths per 100,000 people. Conversely, he focused on states with less laws like Louisiana, which had 18 deaths per 100,000 individuals and Alaska, which had 17.5 deaths per 100,000 individuals.

The study also found that laws requiring universal background checks and permits to purchase firearms were most clearly associated with decreasing rates of gun-related homicides and suicides.

Despite the findings, researchers did not establish a cause and effect relationship between guns and deaths. Rather, they could only establish an association.

That failure illustrates the limits of the study, said Garen Wintemute, an emergency physician and director of the Violence Prevention Research Program at the University of California, Davis.

"Policy makers can really draw no conclusion from this study," Wintemute said, explaining that the study doesn't provide critical answers to which laws work and why.

The larger problem is that the United States effectively stopped doing research on gun laws and violence 15 years ago and now has no evidence that shows causes and effect, he said.

Wintemute added, however, that he believes gun policies are important and can drive rates of violence down. In the future, researchers must look at how several factors including culture, gun ownership, and gun trafficking between states, he said.

Fleegler and his colleagues became interested in the relationship between gun laws and deaths last summer after the Trayvon Martin case sparked conversations about self-defense laws and the use of guns.

Trayvon, 17, was shot dead in a gated Florida community by George Zimmerman, a neighborhood watch volunteer. Zimmerman, who has plead not guilty to a second-degree murder charge, is claiming self-defense.

"There is very minimal research going on and very minimal funding for the research that is going gone," Fleegler said. "We need to understand these relationships so that we can take action."