In a New York Times op-ed piece, former President Jimmy Carter presents revival of the federal "assault weapon" ban, which President Obama supports, as a no-brainer, since the guns that were covered by the expired 1994 law are "designed only to kill police officers and the people they defend." Evidently, if you aim one of these firearms at a home intruder, a prairie dog, or a paper target, instead of firing a bullet it harmlessly unfurls a little flag that says "Bang!" Having polled himself and his hunting buddies, Carter reports that "none of us wants to own an assault weapon, because we have no desire to kill policemen or go to a school or workplace to see how many victims we can accumulate before we are finally shot or take our own lives." According to Carter, then, everyone who owns one of these guns is an aspiring cop killer, homicidal maniac, or both.

Carter never explains what makes these weapons uniquely suited to murdering policemen and random passers-by yet completely inappropriate for any other purpose. On the face of it, the criteria that distinguish "assault weapons" from legitimate, non-cop-killing, non-student-slaughtering guns—which include "military-style" features such as bayonet mounts, folding stocks, and flash suppressors—do not have much to do with criminal functionality. But they must, because Carter says "the results of this profligate ownership and use of guns designed to kill people" (i.e., "assault weapons") include the deaths of "more than 30,000 people" in 2006. In other words, "assault weapons" account for every gun-related death, with none left over for models that don't fall into this arbitrary category. No wonder Carter is so eager to ban them.

Studies of "assault weapon" use prior to the 1994 ban paint a different picture. In these studies, according to a 2004 Justice Department report (PDF), "AWs typically accounted for up to 8% of guns used in crime, depending on the specific AW definition and data source used." Even the shooting rampages for which Carter claims "assault weapons" are especially designed typically involve guns that were not covered by the federal ban. Here is a catalog (PDF), compiled by the Brady Campaign to Prevent Gun Violence, of "Mass Gun Violence in the United States Since 1997." Given that the group is an unrelenting booster of bans on "assault weapons," it presumably would not have missed an opportunity to associate them with mass murder. Yet firearms covered by the federal ban are mentioned in connection with only a small minority of the crimes on the list—nine out of 138, or less than 7 percent, on the first 10 pages. And as I mentioned in a column last month, both the deadliest and the second deadliest mass shootings in U.S. history were accomplished with ordinary handguns.