On September 11, 2001, four sets of pilots and copilots were overcome by terrorists who stormed the cockpits of passenger liners and turned the planes into massive bombs, acts that would lead to three thousand deaths, the destruction of New York City’s Twin Towers, and significant damage to the Pentagon. In the wake of that day’s horrors, many people have begun to wonder if future terrorist acts could be thwarted by giving pilots guns so they could protect their planes against hijackers.

The debate about arming pilots heightened in the summer and fall of 2002. On July 10, 2002, the House of Representatives passed House Resolution 4635, the Arming Pilots Against Terrorism Act, by a 310-113 vote. The House’s action was promptly criticized by the Violence Policy Center (VPC), a pro–gun control organization. In...