Keeping their promise to President Clinton, Republican leaders in Congress have moved quickly to consider a broad range of gun-control laws in the wake of the Littleton attack. Today the Senate will be debating and voting on a range of new proposals, with the House Judiciary Committee set to start hearings tomorrow. Mr. Clinton says that we must "do something" and that he knows "one thing for certain": If more restrictions had been enacted, "there would have been fewer kids killed."

But would more gun laws save lives? There are already a large number of laws in place. The Columbine murderers, Eric Harris and Dylan Klebold, violated at least 17 state and federal weapons-control laws. Mark E. Manes, who allegedly sold the handgun to Harris and Klebold, may have violated at least one federal and one state law, and if either of the killers' parents knew their child possessed a handgun, they would have run afoul of a Colorado law. Nationwide there are more than 20,000 gun-control laws that regulate everything from who can own a gun and how it can be purchased to where one can possess or use it.

Regulations have both costs and benefits, and rules that are passed to solve a problem can sometimes make it worse. The biggest problem with gun-control laws is that those who are intent on harming others, and especially those who plan to commit suicide, are the least likely to obey them. Mr. Clinton frames the issue in terms of whether hunters are willing to be "inconvenienced," but this misses the real question: Will well-intended laws disarm potential victims and thus make it easier for criminals? Potential victims use guns more than two million times a year to stop violent crimes; 98% of the time simply brandishing a gun is sufficient to stop an attack. Crimes are stopped with guns about five times as frequently as crimes are committed with guns.

Consider, then, the costs and benefits of Mr. Clinton's main proposals:

Waiting periods. A three-day waiting period for handgun purchases could not possibly have stopped the Littleton attack, which the killers had been planning for a year. Mr. Clinton focuses on the general benefits from a "cooling-off period," and such benefits might exist. Yet real drawbacks exist, too. Those threatened with harm may not be able to quickly obtain a gun for protection. Experience with the Brady waiting period that lapsed last year, as well as with state waiting periods, indicates that these laws are either neutral or do more harm than good. In the only academic research done on the Brady law, I found that the national waiting period had no significant impact on murder or robbery rates and was associated with a small increase in rape and aggravated-assault rates.

Mandatory gun locks. This proposal, too, is unrelated to the attack in Colorado; Eric Harris and Dylan Klebold would have known how to unlock their guns. Mr. Clinton claims that gun locks will save lives, particularly those of young children. In 1996 30 children under five died in gun accidents--fewer than the number who died of drowning in water buckets. With some 80 million Americans owning 240 million guns, the vast majority of gun owners must be extremely careful or such accidents would be much more frequent.

More important, thousands of children are protected each year by parents or other adults using guns to defend themselves and their families. Mechanical locks that fit either into a gun's barrel or over its trigger require the gun to be unloaded; and locked, unloaded guns offer far less protection from intruders. Thus requiring locks would surely increase deaths resulting from crime. Gun locks may make sense for parents who live in low-crime areas, but this should be a matter of individual choice.

Prison sentences for adults whose guns are misused by someone under 18. Parents are already civilly liable for wrongful actions committed by their children, but Mr. Clinton proposes a three-year minimum prison term for anyone whose gun is used improperly by any minor, regardless of whether the gun owner consents to or knows of the use. This is draconian, to say the least, the equivalent of sending Mom and Dad to prison because an auto thief kills someone while driving the family car.

New rules for gun shows. The Clinton administration has provided no evidence that such shows are important in supplying criminals with guns. What's more, it is simply false to claim that the rules for purchasing guns at a gun show are any different from those regarding gun purchases anywhere else. Dealers who sell guns at a show must perform the same background checks and obey all the other rules that they do when they make sales at their stores. Private sales are unregulated whether they occur at a gun show or not.

If, as Mr. Clinton proposes, the government enacts new laws regulating private sales at gun shows, all someone would have to do is walk outside the show and sell the gun there. To regulate private sales, the government would have to register all guns. Those who advocate the new rules for gun shows should be willing to acknowledge openly if their real goal is registration.

Age limits. Mr. Clinton proposes a federal ban on possession of handguns by anyone under 21. Under a 1968 federal law, 21 is already the minimum age to purchase a handgun, but setting the age to possess a handgun is a state matter. While some people between 18 and 21 use guns improperly, others face the risk of crime and would benefit from defending themselves. My own research indicates that laws allowing those between 18 and 21 years of age to carry a concealed handgun reduce violent crimes just as well as those limited to citizens over 21.

Background checks for purchasers of bomb-making material. This will have little effect, simply because few items are likely to be covered. No one seriously discusses including fertilizer, used to make the bomb that killed 168 in Oklahoma City in 1995, or propane tanks like the ones found after the Littleton massacre. There are simply too many common household items that can be used to make bombs.

Much of the debate over gun control these days is conducted without regard for facts. For example, the press reproduces pictures of a Tech-9, the so-called assault pistol used in the Columbine attack. The pictures show a much larger ammunition clip than was actually used, making it look as frightening as possible. Few reports even mention that at most one of the 13 Littleton victims was killed with this gun. In spite of all the rhetoric and despite its appearance, this "assault weapon" functions no differently from other semiautomatic pistols sold in the U.S. It is no more powerful, it doesn't shoot any faster, and it doesn't shoot any more rounds. One pull of the trigger fires one bullet.

Good intentions don't necessarily make good laws. What counts is whether the laws will ultimately save lives. The real tragedy of Mr. Clinton's proposals is that they are likely to lead to the loss of more lives.