Today I filed an amicus brief in Duncan v. Becarra, a challenge to a California statute confiscating almost all magazines over 10 rounds. Last summer, a federal district court issued a temporary injunction against the confiscation statute. The case is now before a panel of the 9th Circuit Court of Appeals.

The amicus brief mainly addresses the standard of review. The Supreme Court's decision in District of Columbia v. Heller categorically forbids the prohibition (or confiscation) of arms that are "in common use" and "typically possessed by law-abiding citizens." The standard magazines that firearms manufacturers provide for their guns–such as a 12 or 17 round magazine for a semi-automatic pistol–easily meet this standard. Indeed, they constitute nearly half of all magazines.

It is a misnomer to say that standard magazines are "large capacity." The brief does not address genuinely "large" magazines, such as the aftermarket 50 round magazines that are available for some firearms. Instead, the brief concentrates on the types of magazines that have been standard on American firearms for decades.

Although courts have upheld standard magazine bans by applying a feeble version of intermediate scrutiny, we urge the 9th Circuit to adhere to Supreme Court precedent.

The brief suggest that the Circuit Court should ignore arguments about whether standard magazines are "necessary" for self-defense. In Heller, the Supreme Court found that handguns were constitutionally protected because they were commonly chosen by law-abiding Americans for lawful self-defense. Whether long guns were an adequate alternative means of self-defense was irrelevant to the Heller majority. Likewise, standard magazines are commonly chosen for self-defense. Because standard magazines are, beyond dispute, "typical" and "common, prohibition is off the table–to the extent that courts choose to obey Heller.

The brief also addresses some empirical issues. It explains that the evidence before the Court indicates that standard magazines are not disproportionately used in mass shootings. Moreover, even though lawful defenders usually do not fire more than 10 shots, the reserve capacity provided by standard magazines helps to reduce the risk that lawful defenders will be injured by their assaillants:

The awareness that a defensive shooter is capable of firing enough rounds to defuse the threat affects every party to a potential attack. Reserve capacity is a credible deterrent to criminals–especially for a victim confronted by multiple assailants. For example, the five criminals chased off by the Detroit woman in the example above would have had less reason to fear her if she had only a 5-shot revolver. Additionally, a defensive shooter can confidently act knowing she will not suddenly exhaust her ammunition and become a defenseless victim–like the Texan woman in the example above. Violent confrontations are inherently unpredictable. As [Florida State U. criminology professor Gary] Kleck explained, "victims of crimes generally cannot plan for or anticipate crimes to occur at a specific time and place … Victims who wish to defend themselves with firearms usually have to make do with a single available gun and its ammunition capacity." If a victim sees one assailant, she cannot know if a second assailant may be hiding nearby. If she sees two, there may be three. When a defender has a greater reserve, she will fire more shots at the first attacker knowing that she will have sufficient ammunition to deal with a possible second or third attacker. Obviously, the more shots the defender fires, the greater the possibility that the attacker(s) will be injured and the lesser the chance that the defender will be injured. Moreover, when a defender has only a limited number of shots, she must make a calculation before each shot to determine whether she can successfully make a threat-ending shot now or whether it is worth the risk to wait a few moments in hopes of a better opportunity. These critical moments the defender spends hesitating and analyzing the situation could be the difference between life and death. By constricting reserve capacity, California's ban increases the risk of injury for victims and reduces it for attackers. That is the opposite of the Second Amendment's intent and purpose.

The amicus brief is on behalf of Doctors for Responsible Gun Ownership, the Independence Institute (where I work), and the Millennial Policy Center (where the brief's lead author, Joseph G.S. Greenlee, is a policy fellow). Plaintiffs in Duncan v. Beccaria are represented by the law firm Kirkland & Ellis and by the Michel & Associates firm. Former U.S. Solicitor General Paul Clement is the counsel of record. The date for oral argument will be set sometime after California Attorney General Xavier Beccaria files his reply brief in a few weeks.