In his poignant, emotional address to the nation Sunday night, President Obama said that following the massacre of 20 children and six adults in Newtown, Conn., "we will have to change."

Though he didn't specify exactly what kind of change he is looking for, it certainly sounded as if he is ready to sign some gun-control legislation.

"No single law, no set of laws can eliminate evil from the world or prevent every senseless act of violence in our society, but that can't be an excuse for inaction," Obama said.

Some in Congress are ready to act. Sen. Dianne Feinstein, D-Calif., announced Sunday that she will introduce a ban on the sale, transfer, importation and possession of assault weapons and big clips, drums or strips of more than 10 bullets.

Feinstein was the author of a previous assault-weapons ban that ran from 1994 through 2004. Following the ban, the Department of Justice reported in a 2004 study, the share of gun crimes involving assault weapons declined by 17 to 72 percent in the six cities that were examined. The study added that such declines were "consistent" with national data patterns.

The department's study also found, however, that a renewal of the ban wouldn't be any panacea: "Effects on gun violence are likely to be small at best and perhaps too small for reliable measurement," it notes, due in part to an exemption for pre-ban assault weapons (Feinstein has indicated that such an exemption also would be part of her new bill).

Still, a ban is well worth instituting, especially if this nation is serious about preventing more large-scale shootings like the tragedy in Newtown - not to mention the smaller-scale but no less deadly mayhem that is endemic to American life. The few studies that have looked at gun violence from semiautomatic weapons, including assault weapons, suggest that they result in more shots, more people being hit and more damage inflicted per victim than attacks with other guns. After Feinstein introduces her legislation, Congress needs to let it get a floor vote - something it hasn't done with attempts to revive the previous ban since it expired in 2004.

There are other measures that we urge Congress to also consider on gun control. There are mandatory federal background checks on individual firearm sales from registered dealers - checks that blocked 1.6 million gun sales from 1994 to 2007 - but none is mandatory when a gun is bought from an unlicensed dealer.

That's an enormous exemption, given that some 40 percent of guns are purchased from unlicensed dealers. Felons, the mentally ill, people with restraining orders - all of these people can easily and legally buy guns, thanks to this loophole.

From a public safety perspective, this makes no sense. Everybody should be subject to the same rules, especially when it comes to something as deadly as a gun. This would also be a sensible and politically possible restriction.

Congress needs to act on gun control, and it needs to do so now.