Today (three weeks late!) Sen. Dianne Feinstein finally followed through on her threat to introduce a new federal ban on "assault weapons." Or so news reports claim. So far I have not been able to locate an actual bill, and The Washington Post reports that Feinstein was still fiddling with the text yesterday. There is no link to the bill on Feinstein's website, and the lines at her office are too busy for me to get through, presumably because many other people are wondering where the hell the bill is. So for now all I have to go on is the summary that her office posted in December, plus the details that her aides have divulged to the press.

The bill bans the manufacture and sale of more than 100 guns by name, including the Bushmaster rifle that Adam Lanza used to murder 26 people at Sandy Hook Elementary School in Newtown, Connecticut, last month. That may seem emotionally satisfying, but it would have been equally logical to ban the car he drove to the school. After all, had he not been able to reach the school, the massacre never would have happened. Even if the particular model of car that Lanza used to commit his crimes had been unavailable, of course, he could have driven a different, equally effective car. Yet for people who think like Dianne Feinstein, it is inconceivable that such substitution might occur with guns as well as cars.

In addition to the specifically listed guns, Feinstein's bill, like the "assault weapon" ban that expired in 2004 (which she also sponsored), covers guns that accept detachable magazines and have military-style features such as pistol grips, folding stocks, and flash suppressors. But while a rifle needed two military-style features to qualify as an "assault weapon" under the old law, it needs only one under the new bill. That might count as an improvement if these features had anything to do with the ability to kill defenseless schoolchildren and moviegoers, but they don't. Judging from her office's summary, here are the features Feinstein considers especially menacing: pistol grips, folding stocks, thumbhole stocks, and grenade launchers (not very useful unless you have grenades, which are already illegal for civilians).

This sort of legislation makes sense only to people who don't understand what it does. The folks at CNN, for example, who put this headline on their story about Feinstein's press conference: "Feinstein Proposes New Ban on Some Assault Weapons." Since "assault weapons" are defined by law, how is it possible for the law that defines them to cover only some while missing others? In case that's not confusing enough, CNN adds that "not all of the weapons in the bill meet the technical definition of assault weapons." What "technical definition"? It can't be Feinstein's, since any gun covered by her bill is an "assault weapon" by (arbitrary) definition. Maybe CNN corresponents Dana Bash and Tom Cohen mean that Feinstein's definition is different from Connecticut's, which is essentially the same as the old federal definition; or California's, which is broader; or New York's, which is based on a somewhat different list of military-style features. More likely, they do not know what they mean. Evidence for the latter conclusion:

Supporters of more gun control acknowledge the constitutional right to bear arms, but argue that rifles capable of firing multiple rounds automatically or semi-automatically exceed the reasonable needs of hunters and other gun enthusiasts.

It is amazing that, a quarter of a century after California passed the first "assault weapon" ban, journalists who cover this issue still think such laws are 1) aimed at machine guns, 2) aimed at all semiautomatics, or 3) both, as Bash and Cohen seem to believe. But maybe we should not be too hard on them. After all, President Obama, who supports Feinstein's bill, suffers from a similar misconception.

Even if you accept Feinstein's false premise that there is something especially assaulty or murdery about the guns she wants to ban, her bill would not actually get rid of them, since millions of existing "assault weapons" would remain in circulation. Feinstein says her aim is to "dry up the supply of these weapons over time." But guns are durable products that remain usable for decades, not a puddle that evaporates when the sun comes up. Feinstein claims her bill will "help end the mass shootings that have devastated countless families and terrorized communities." How exactly will it do that?