Likewise, law professor Glen Reynolds writes, "Pearl, Miss., school shooter Luke Woodham was stopped when the school's vice principal took a .45 from his truck and ran to the scene. In [last] February's Utah mall shooting, it was an off-duty police officer who happened to be on the scene and carrying a gun."
It's impossible to know exactly how often guns stop criminals. Would-be victims don't usually report crimes that don't happen. But people use guns in self-defense every day. The Cato Institute's Tom Palmer says just showing his gun to muggers once saved his life.
"It equalizes unequals," Palmer told "20/20". "If someone gets into your house, which would you rather have, a handgun or a telephone? You can call the police if you want, and they'll get there, and they'll take a picture of your dead body. But they can't get there in time to save your life. The first line of defense is you."