The best available evidence suggests two major National Rifle Association gun policy prescriptions — what are known as “stand your ground” self-defense laws and permissive concealed carry laws — increase homicides and violent crime.

That is according to a massive new study by the RAND Corporation, an independent think tank. The group's experts scoured thousands of academic papers on gun violence in an effort to make definitive statements about how gun policies affect crime and safety. They winnowed that list down to only the highest-quality studies — just 62 in total — containing evidence capable of establishing a causal link between a gun policy change and a specific outcome.

Because the RAND researchers' criteria for including studies in their final analysis were rigorous, for the majority of policies and outcomes, there was not enough good research to make any definitive statements — a clear indication of how little we know about how to prevent gun violence. But there were notable exceptions.

There is moderate evidence, for instance, that “stand your ground” laws, which remove the requirement for gun owners to attempt to retreat from a situation before using lethal force, increase total rates of homicide. A 2013 study, for instance, found that states passing such laws saw 6 percent to 11 percent increases in their total homicide rate. Another study found that Florida experienced a significant 24 percent increase in total homicides and 32 percent increase in firearm homicides following enactment of the stand-your-ground law in 2005.

https://www.washingtonpost.com/news/wonk/wp/2018/03/02/the-best-available-evidence-suggests-nra-backed-gun-policies-are-making-crime-worse/?utm_term=.181295d6ec07