It appears that the Virginia Tech murderer was a resident alien. Did this mean someone broke the law by selling him the guns? (Naturally, the killer showed himself to be unconcerned about following the law, but the premise of some gun control laws is that they may deter generally law-abiding people from selling guns to those who might be dangerous.)

I don't think so. Federal law bars most nonresident aliens, including illegal aliens, from possessing a gun, but treats resident aliens the same as citizens. Virginia law likewise doesn't bar gun ownership by resident aliens, and even allows them to get concealed carry permits.

Some states or cities have banned gun ownership by aliens, or at least aliens who hadn't declared an intent to become citizens. (See here for my criticism of one such law, in Omaha.) Such laws may violate the federal Equal Protection Clause, by discriminating against noncitizens without adequate justification; but the one case I've seen on the subject, State v. Hernandez-Mercado, 124 Wash. 2d 368 (1994), rejected such a challenge.

The laws may also violate state constitutional provisions, if the provision isn't limited to citizens. The Washington Constitution's provision is limited to citizens; but the Michigan Constitution is not — it says "Every person has a right to keep and bear arms for the defense of himself and the state" — and the Michigan Supreme Court accordingly struck down a ban on gun possession by noncitizens in People v. Zerillo, 219 Mich. 635 (1922). (At the time, the Michigan provision differed slightly — it omitted "keep and" — but not materially.)

The Utah Supreme Court upheld a ban on gun possession by noncitizens in State v. Vlacil, 645 P.2d 677 (Utah 1982), despite a constitutional provision stating, "The people have the right to bear arms for their security and defense, but the legislature may regulate the exercise of this right by law." It is possible (though in my view mistaken) to read "the people," as opposed to Michigan's "every person" or Nebraska's "all persons," as referring to individuals — which Utah courts have done as to the right to bear arms — but only to individuals who are full members of the American polity. But the Utah Supreme Court didn't even do that; it simply cited to State v. Beorchia, 530 P.2d 813 (Utah 1974), which reasoned that "It is quite evident from [the constitutional text] that the Legislature had sufficient power to enact thestatute in question." In my view, it is not at all evident that the power to regulate the exercise of a right includes the power to deny the right to whatever group the legislature chooses.

If banning gun ownership by noncitizens is constitutionally permissible, is it a good idea? I don't think so. It seems to me that resident aliens, at least, and perhaps legal but nonresident aliens, are just as morally entitled to try to defend their lives against crime as citizens; their ability to do so is just as valuable to society as citizens' ability to do so; and they seem no more likely than citizens to use the guns to cause harm. Moreover, in a nation with over 200 million firearms in private hands, it seems highly unlikely that the rare noncitizen with mass murder on his mind will indeed be stymied by laws banning gun possession by noncitizens, and will be stopped from getting a gun on the black market. That unlikely possibility of social benefit is substantially outweighted by the cost of denying millions of law-abiding noncitizens of their ability to effectively defend themselves.

Please correct me if I've misunderstood the often quite complicated federal and state gun laws that govern resident aliens; but I'm pretty sure I read them correctly.

UPDATE: A correspondent informs me that "there is one difference between treatment of citizens and resident aliens. Resident aliens have to provide extra identification to prove 90 days' residence in the state. See 27 CFR sec. 478.124(c)(3)(ii)." I appreciate the extra information, though it does not much affect the big picture analysis. (One could argue against even this requirement, given that it creates a fairly long waiting period for buying a gun in certain situations; but this nonetheless seems a relatively small detail relative to the broader question of whether non-citizens should be able to own firearms.)