THE COMMON REFRAIN of those who oppose limits on gun sales and gun ownership is that we must support vigorous prosecution of criminals who use guns. Don't limit the rights of law-abiding people who want guns for sport or protection, they say, but throw the book at people who abuse those rights. As Virginia, Maryland and federal authorities squabble over who gets to prosecute first in the sniper killings that terrified this region for three weeks, we can see this philosophy in action. We certainly support a vigorous prosecution of the two alleged assailants, if the evidence holds up (though not the frenzy to subject an apparent juvenile to the death penalty). But even convictions in each of the 10 murders and three woundings would be less satisfying than it would have been to prevent the shootings, by keeping guns away from potential criminals, or to solve them sooner, by maintaining better registries of gun owners and ballistic fingerprints. Being tough after the fact is only partial comfort.

Ah, there they go again, the NRA will say -- exploiting a tragedy to make a political point. Well, yes. If trying to learn from sad experience and develop sound policies to make such experiences less likely in the future constitutes exploitation, we plead guilty. And we acknowledge that much remains unknown about this case. It seems that John Allen Muhammad was able to buy a gun illegally, exposing again the weaknesses in the nation's background-check system; he was under a court restraining order that should have barred the sale. It seems that a man who had been found in court to have illegally taken control of his children, who had threatened to kill his ex-wife, according to her allegation -- it seems that such a man had no trouble buying the civilian facsimile of an M-16 rifle and the scope to go with it, and apparently other guns as well. It seems that a national ballistics registry of the sort that only Maryland and New York have instituted might have given investigators a boost as they tried to solve these murders. But many details have yet to come out about this case, and some of these early impressions may not hold up.

What we do know for sure is that the 10 deaths and three woundings that prosecutors will now attribute to John Muhammad and John Lee Malvo represent a minuscule addition to the epidemic of gun violence in this country. More than 75 people die each day as a result of gunfire, whether suicidal, homicidal or accidental. It is an epidemic that routinely terrifies children in neighborhoods that were little affected by this shooting spree; an epidemic whose victims -- both the injured and the loved ones of the dead -- suffer for years without any of the public attention devoted to the events of the past three weeks. No law could eliminate gun violence, but the epidemic, through sensible public policy, could be controlled. It does not strike us as exploitative to point out that, in failing to control it, the nation is making a choice, not giving in to a fact of nature.