Sen. Dianne Feinstein (D-Calif.) was not happy with the gun control hearing that the Senate Judiciary Committee held on January 30, where two witnesses spoke in favor of her proposed "assault weapon" ban and three spoke against it. So she arranged another hearing before the same committee, which was held yesterday. It featured five witnesses who support her bill and three who oppose it, so Feinstein is now ahead by one witness. But critics of her legislation made up for their numerical disadvantage with substance. When you read the testimony of the two sides, the clearest difference is that opponents of the Feinstein bill, S. 150, know what they are talking about, while its supporters don't.

The most sophisticated pro-ban testimony yesterday came from John Walsh, the U.S. attorney for Colorado, who concedes that the 1994 ban on "assault weapons," which was also sponsored by Feinstein and expired in 2004, "resulted in certain manufacturers producing and selling firearms of equivalent functionality and lethality." That was possible because the law's definition of "assault weapon" hinged on functionally insignificant features such as barrel shrouds and bayonet mounts. Walsh claims "current proposals under consideration substantially address the gaps in the 1994 statute," but he does not explain how. The new, supposedly improved "assault weapon" ban features a longer list of firearms that are banned by name; an appendix, comprising most of the bill, listing 2,258 models that are explicitly not banned; and a somewhat different list of forbidden features that still have very little to do with a gun's usefulness to mass murderers or other criminals. Walsh says "the key features of these weapons are the ability to fire at high velocities and to accept high-capacity magazines." Yet Feinstein's bill says nothing about muzzle velocity and exempts many guns that accept high-capacity magazines.

Even more egregiously misleading was the testimony of William Begg, a Connecticut emergency room physician who emphasized the difference between .22-caliber handgun rounds and .223-caliber rifle rounds like those used in the Sandy Hook massacre. Above is a picture Begg included in his testimony, which according to The New York Times also featured "a video of two bullets being fired into beige, gelatinous material resembling flesh." As the Times describes it, "One was from a handgun, the other from an AR-15, a popular style of assault rifle. The footage revealed far more tearing and damage from the AR-15."

At the risk of stating the obvious, it should be noted that .22-caliber weapons can be used to kill innocent people; a Walther P22 was one of the two guns (along with a Glock 19) used to kill 32 people at Virginia Tech in 2007, which was the second biggest massacre at a school in U.S. history. (The biggest one invoved explosives.) Still, Begg is right that, other things being equal, a larger projectile does more damage. But Feinstein's definition of "assault weapon" has nothing to do with caliber. It is simply wrong to suggest that the guns she wants to ban are distinguished from the guns she exempts based on the kind of ammunition they fire.

For example, as Second Amendment scholar David Hardy notes in his testimony, S. 150 specifically exempts the Ruger Mini-14, which fires the same .223-caliber ammunition as the Bushmaster M4 carbine used by Adam Lanza in Newtown. (Hardy observes that "the main difference" between the Mini-14 and the AR-15-type guns Feinstein wants to ban "is that the Mini-14 has a conventional wooden stock and looks 'traditional.'") "The ammunition used in the typical 'assault weapon' exhibits intermediate ballistics," notes Fordham University law professor Nicholas Johnson, who testified before Hardy. "On this objective measure the class is less destructive than most rifles used for hunting medium to large game."

Johnson also emphasizes the destructive power of "the common repeating shotgun, either pump or semiautomatic," which Feinstein likes so much that she lists hundreds of models that are not covered by her bill:

In 12 gauge configuration, with a three inch, 00 buckshot load, any of these guns will fire fifteen, .33 caliber, 60 grain projectiles with a single pull of the trigger. With aminimum magazine capacity of five rounds and one chambered, that is ninety, . 33 caliber projectiles fired with 6 trigger pulls…. Additionally, this broad category of repeating shotguns can be continuously reloaded without disabling the gun. That is an attribute that the prohibited class does not exhibit.

Johnson adds that while "assault weapons" are inaccurately described as "spraying" bullets, "the shotgun actually does fire a cloud of projectiles that spreads as it moves downrange." He also quotes a 1997 U.S. Army assessment that found "the probability of hitting a man sized target with a shotgun was superior to that of all other weapons" up to a range of 30 yards. So why are shotguns deemed legitimate, while firearms that are in some ways less dangerous (and are used less often in crimes) are considered an intolerable threat to public safety? Notably, Dr. Begg did not show what an ordinary shotgun does to gelatinous material.

Hardy and Johnson both show that, contrary to John Walsh's assurances, the distinctions drawn by Feinstein's bill remain nonsensical. "'Semiautomatic assault rifle' is internally contradictory and thus meaningless," Hardy writes, since a true assault rifle can fire automatically. "Drafters of legislation are thus forced to define what they would restrict in ways that are arbitrary and irrational." Feinstein's bill is so arbitrary and irrational, Johnson argues, that it would fail even the most permissive level of judicial scrutiny. He calls the legislation "simply incoherent," saying "the classifications created by the bill do not pass even a rudimentary rational basis review." And since the Supreme Court has identified the right to keep and bear arms as a fundamental right protected by the Second and 14th Amendments, laws that impinge upon it should receive more scrutiny than that.

In December I asked, "How Stupid Must a Gun Law Be to Get Struck Down by the Courts?" Last month I noted that people who want to ban "assault weapons" typically don't know what they are. In The Orange County Register this week, I highlighted some of the puzzling choices Feinstein made in writing her bill.