I'm going to leave analysis of the tortured exegesis of the text of the Second Amendment to others (at least for now), but I feel compelled to comment on the peculiarity of Justice Scalia's analysis of what kinds of weapons are covered by the 2nd Amendment. In essence, he says that handguns and rifles are okay because they were the kinds of weapons that someone might have used in a late 18th-century militia, but that more modern weapons can be prohibited. Here's an example of this kind of reasoning, which appears in several places in the opinion:

It may be objected that if weapons that are most useful in military service—M-16 rifles and the like—may be banned, then the Second Amendment right is completely detached from the prefatory clause. But as we have said, the conception of the militia at the time of the Second Amendment’s ratification was the body of all citizens capable of military service, who would bring the sorts of lawful weapons that they possessed at home to militia duty.

As I read this, it occurred to me that modern handguns are nothing like the weapons that were commonly available in the 1790s. Pretty much all of the handguns in those days were muzzle loaders, which took a while to shoot, and required a lot of time between shots. The first practical revolver wasn't invented until about 20 years later, and Colt didn't get his patent until 1835. The predecessors of today's semiautomatic guns didn't appear until much later, around the 1870s. Simply put, a handgun in the 1790s was nothing like a handgun today, except that both can be held in your hand and both shoot bullets.

Of course, Scalia doesn't mean that governments can ban weapons that didn't exist in the 1790s. Still, you have to wonder how to reconcile the idea that the more dangerous weapons used by the military today or a sawed-off shotgun can be banned with the idea that a handgun that can shoot 15 rounds in a matter of seconds - a rate that probably exceeds that of a muzzle-loader by a couple of orders of magnitude - cannot.