[KarlInOhio]

SCALIA: We'll see. Obviously the Amendment does not apply to arms that cannot be handcarried - to keep and bear, so it doesn't apply to cannons, but I suppose there are handheld rocket launchers that can bring down airplanes that will have to be decided.

Generally I defer to Scalia on his Constitutional knowledge, but I have to point out something. The Constitution gave Congress the power to "To declare War, grant Letters of Marque and Reprisal, and make Rules concerning Captures on Land and Water". The letters of marque and reprisal essentially give private individuals the authority to make war on enemies of the country. Most often they were issued to ships' captains to act as privateers. Since Congress wasn't passing out cannons, that implies that private individuals already owned the cannons necessary to make war and capture enemy ships.