The main mechanism for keeping firearms out of the hands of felons and the mentally ill is the National Instant Criminal Background Check System, run by the FBI. If you try to buy a gun from a federally licensed firearms dealer and your name is on the list of disqualified buyers, the dealer will refuse to sell to you.
Yet anyone can buy a firearm from a private seller, at a gun show or elsewhere, without having to be cleared by the system, and as many as 40 percent of all gun sales are made privately. Leaving this gun-show loophole open is madness, yet the NRA has fought tooth and nail all attempts to close it.
A better system of detecting and treating people with a mental illness that makes them prone to violent behavior, and making sure their names are promptly put on the check list, could make mass shootings such as Columbine and Virginia Tech less likely to happen.
If the Newtown tragedy doesn't lead, at last, to productive dialogue on all sides about better ways to balance gun rights with the right to live in safety, then the next mass shooting will be just a matter of time.
Craig R. Whitney, a former assistant managing editor and foreign correspondent for the New York Times, is author of "Living with Guns: A Liberal's Case for the Second Amendment," published by Public Affairs last month.