That's a good question, because nobody has ever made that case. No one has ever said how you get from point a to point b. The case wasn't made when the bill was introduced and it has never been made, from then until now. Criminals still have firearms. Our police friends see this every day. Criminals still get them, so I guess the registration didn't work. We've had registration of handguns since 1934.
On November 17th, 2011. See this statement in context.