The surprising discovery is that of all the amendments that comprise the Bill of Rights, the Second was probably the least debated. What we know is that the founders were deeply opposed to a standing army, which they viewed as the first step toward tyranny. Instead, their assumption was that the male citizenry would all belong to local militias. As Waldman writes, “They were not allowed to have a musket; they were required to. More than a right, being armed was a duty.”

Thus the unsurprising discovery: Virtually every reference to “the right of the people to keep and bear Arms” — the second part of the Second Amendment — was in reference to military defense. Waldman notes the House debate over the Second Amendment in the summer of 1789: “Twelve congressmen joined the debate. None mentioned a private right to bear arms for self-defense, hunting or for any purpose other than joining the militia.”

In time, of course, the militia idea died out, replaced by a professionalized armed service. Most gun regulation took place at the state and city level. The judiciary mostly stayed out of the way. In 1939, the Supreme Court upheld the nation’s first national gun law, the National Firearms Act, which put onerous limits on sawed-off shotguns and machine guns — precisely because the guns had no “reasonable relation” to “a well-regulated militia.”