Florida's controversial "Stand Your Ground" law, which gained national attention following the 2012 shooting death of Trayvon Martin, has been linked to a significant increase in gun-related homicides, according to a new study.
Published Monday in the Journal of the American Medical Association (JAMA) and led by the University of Oxford, the first-of-its-kind paper found that the implementation of Florida's self-defense law — which removes the duty to retreat when confronted with a perceived deadly threat — was associated with a 24.4 percent increase in homicides and a 31.6 percent increase in firearm-related homicides.
In 2005, Florida was the first state to enact a Stand Your Ground law, and some two dozen states have since followed suit.
"Our hypothesis was that these laws prevent people from taking alternative actions instead of using firearms in critical situations," Antonio Gasparrini, an associate professor at the London School of Hygiene and Tropical Medicine and a co-author of the study, told NBC News.
He added that the purpose of the study was to fill a gap in research on the impact of such legislation, not to further a political agenda.
"We just hope this evidence can be used to form a discussion on the pros and cons of these kinds of laws," said Gasparrini. "We don't have a preference about how this evidence will be used."
Using data from the Centers for Disease Control and Prevention and the Wide-ranging Online Data for Epidemiologic Research (WONDER), the study analyzed the monthly rates of homicide in Florida between 1999 and 2014. Prior the law's implementation in 2005, researchers found the mean monthly homicide rate in Florida to be 0.49 deaths per 100,000 and the rate of homicide by firearm to be 0.29 deaths per 100,000.
After the law took effect, researchers found "an abrupt and sustained increase" in both the monthly homicide rate and in the rate of homicide by firearm. The monthly homicide rate increased 24.4 percent, the study states, while the rate of homicide by firearm rose 31.6 percent.
To account for other factors that may have been contributing to the increase in homicide rates, researchers also looked at rates in four other states — New York, New Jersey, Ohio and Virginia — that did not implement Stand Your Ground laws.
"We think this design is very robust to reassure us that what we found was actually an effect of the law and not other policies or phenomena occurring within that time period," Gasparrini said.
Stand Your Ground laws — sometimes derided by critics as "Shoot First" laws — became the subject of widespread scrutiny during the trial of George Zimmerman, who in 2012 shot and killed Martin, an unarmed black teen. Although Zimmerman's lawyers did not ask for an immunity hearing under the self-defense law, instructions given to the jury in that case borrowed language from the statute. Zimmerman was found not guilty.
The National Rifle Association, which strongly supports Stand Your Ground laws, did not respond to NBC News' request for comment on the JAMA study.