What clearly doesn’t work is the policy of designating public schools—or any venue where large numbers of people congregate—as “gun-free zones.” After last summer’s slaughter at a movie theater in Aurora, Colorado, political scientist John Lott noted that the location wasn’t the closest to the killer’s apartment or the one with the largest audience. “Instead,” Lott observed, “out of all the movie theaters within 20 minutes of his apartment showing the new Batman movie that night, it was the only one where guns were banned.” In Colorado, individuals with permits can carry concealed handguns in most malls, movie theaters, and restaurants. But private businesses can determine whether permit holders can carry guns on their private property.

Though ignored by most of the media, some mass school shootings have been stopped because an authority figure with access to a firearm intervened. In 1997, at Pearl High School in Mississippi, 16-year-old Luke Woodham shot nine students and staff, killing two, before Joel Myrick, the school’s assistant principal, confronted and subdued him with a pistol he retrieved from his truck. In 2001, senior Jason Hoffman opened fire on the attendance office of Granite Hills High School in El Cajon, California. Hoffman wounded five people before being shot and incapacitated by an armed school cop. Even the shootings at Columbine High School in Colorado, horrible as they were, could have been even worse but for the intervention of Neil Gardner, an armed Jefferson County sheriff’s deputy having lunch on campus at the time. Gardner exchanged fire with one of the shooters and summoned help, giving several students a chance to escape.