Tens of thousands of firearm dealers across the country will now be required to run background checks on buyers. On Thursday, the U.S. Department of Justice and Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) finalized a new rule, which mandates people who sell guns online, by mail, or at flea markets and firearm shows verify their buyers can legally purchase guns.

Dr. April Zeoli spoke with Fox 17 about the evidence base behind such policies and what the data shows when they are implemented effectively.