Which Gun Laws Work?

Studies have found that a combination of laws seems have greater effects than individual laws working alone. For example, one study that Wintemute was a part of examined states whose laws included a three-part punch: Gun sellers had to run background checks on buyers; buyers had to apply for a permit; and owners had to register their firearms. Compared to states that were missing either a permitting or a registration law, states with all three were four times less likely to have guns coming in that were used in a crime soon after their purchase. (When guns move quickly from seller to crime scene, that's a clue there are criminal systems set up where guns that appear to be legally purchased are actually getting funneled to illegal channels.)

Of course, research finds that criminals tend to traffic arms into states with numerous gun-control laws, from states with fewer ones. Fortunately, there's a way to stem the flow. Two studies found that laws instructing gun-owners to immediately file a report when their guns are lost or stolen keep out-of-state weapons from showing up at crime scenes.

There's one line of research that's shown certain laws are associated with fewer homicides. Two studies found that after states pass laws keeping people who are under domestic violence restraining orders from obtaining guns, fewer state residents get killed by their spouses or other romantic partners.