That could mean al-Qaida has a good-sized secret domestic arsenal by now. Or it could mean that a lot of people thought to be a mortal threat were about as bloodthirsty as Jill Biden.
The more interesting question is whether any of the purchases led to terrorist violence. If supporters of the bill had examples to flog, you can be sure they would. In any event, the FBI keeps track of anyone on the list who buys a gun and sometimes steps up surveillance in response.
The proposed law wouldn't have impeded Shahzad because he didn't make the list until after he bought the rifle. Nidal Hasan, the alleged Fort Hood shooter, failed to get a nomination.
Most of the people on the terrorist roll, as it happens, can't buy guns legally anyway, because most of them are not Americans. Under federal law, firearms may be purchased only by U.S. citizens or legal resident aliens.
Barring gun sales on the basis of mere suspicion might be permissible except for that pesky Second Amendment. The Constitution doesn't specifically enshrine the right to ride in a commercial airliner or even the right to travel. The right to own a gun, by contrast, is right there in black and white.
Not only that, but someone blocked from boarding a plane can always travel by train, bus, boat or car, says UCLA law professor Eugene Volokh, which is one reason courts have upheld restrictions on flying. "But this completely prohibits you from even possessing a gun," he notes, once you've gotten notice that you are forbidden to buy one.
All this would happen without the normal requirements of due process, which makes it unconstitutional as well as unwise. Note to the federal government: You are entitled to deny firearms to anyone engaged in efforts to commit acts of terrorism -- just as soon as you can prove it.