MALE: The fact is we do have statutes, both at the federal and state level that prohibit classes of people from being in possession of firearms. If you're under 18 in Virginia you can't walk around with a gun. If you're an illegal immigrant, if you're a convicted felon, if you've been adjudicated in same, these things are already illegal. So, what we're really asking about is a question of prior restraint. How can we prevent future crime by identifying bad guys before they do anything bad? And, the simple answer is you can't.
And, particularly, under the legal system we have in the United States there are a lot of Supreme Court opinions that say, "No, prior restraint is something that the government does not have the authority to do." Until there is an overt act that allows us to say, "That's a bad guy," then you can't punish him.