Obama made a powerful emotional case for stricter anti-gun legislation yesterday, a case that few Americans heard unless their minds were already made up on the issue. And if some undecided American had happened to hear Obama’s speech, odds are they would have come away thinking, “Absolutely. I would do anything to keep my kid from getting shot.”

And that is why Obama’s speech will fail. It has no limiting principle.

In their more honest moments, anti-gun activists will readily admit that a more comprehensive government monitoring system of gun sales would have done anything to prevent the Sandy Hook Elementary School massacre that took place in December. The shooter had no criminal record before he killed, so he would have passed a criminal background check. The killer’s mother, who purchased the weapons, also was not a criminal. Sen. Richard Blumenthal, D-Conn., basically admitted background checks were ineffective to CNN’s Candy Crowley when she asked him, “How would anything in the bill, as it currently stands, have stopped anything that went on in Newtown?” Blumenthal could not identify a single scenario that would have prevented Sandy Hook.