‘Accoutrements’: The Founding-Era Word Doing All the Work in California’s Magazine Ban Just Got Called Out at the Supreme Court
Challengers to California’s magazine ban say two federal appeals courts now give opposite answers to the same Second Amendment question, and the Supreme Court already has two rifle-ban cases on its docket.
The Duncan v. Bonta magazine ban challengers just handed the Supreme Court its best reason yet to stop stalling. In a supplemental brief filed Monday on docket 25-198, the Bruen team at Clement & Murphy told the justices that two federal appeals courts now read the same Second Amendment and hand back opposite answers.
The question sounds simple: is a magazine that holds more than ten rounds an “arm” the Constitution protects? The Ninth Circuit’s answer is no. Magazines are “accoutrements,” a Founding-era category that, by the court’s own history lesson, covered flint, scabbards, holsters, and cartridge boxes.
That one word carries the whole ban. If a magazine is an accoutrement, the Second Amendment’s text never reaches it, and California can criminalize whatever capacity it likes.
The split: On July 17, the en banc Third Circuit ruled 10-5 that New Jersey’s ban on magazines over ten rounds violates the Second Amendment, striking the state’s so-called “assault weapons” ban in the same opinion. Its conclusion was one sentence: “Bans on weapons in common use for lawful purposes are unlawful.”
The Third Circuit took up the accoutrement theory by name and rejected it. Magazines are arms, it held, and nothing in the Second Amendment’s text says protection runs out at round eleven.
Even the historical record got graded twice. The Ninth Circuit leaned on Founding-era gunpowder-storage rules to justify California’s cap; the Third Circuit read the same laws and called them fire-safety codes, not firearms regulation. Same archive, opposite conclusions.
Where you stand: In New Jersey, Pennsylvania, and Delaware, standard-capacity magazines now sit under binding precedent calling them protected arms. In the Ninth Circuit’s territory, the opposite rule stands, and California’s possession ban keeps its teeth. Same Constitution, different answer, depending on where you keep your range bag.
The stall: The Duncan v. Bonta magazine ban petition has been parked at the Court since August 2025, and the docket shows it distributed for conference more than twenty times without a grant or a denial. (We counted.) A relist streak that long isn’t neglect. It’s a Court waiting for something.
That something may have arrived on June 30, when the justices granted review in Viramontes v. Cook County and Grant v. Higgins, consolidated cases asking whether states can ban AR-15-style rifles in common use. Duncan’s lawyers argue the magazine question belongs in the same term, through their case or through Gator’s Custom Guns v. Washington (docket 25-153), the parallel challenge to Washington’s ban waiting in the same line.
The logic is hard to dodge: if the Court is deciding whether a state can ban the rifle, whether a state can ban the thing that feeds it is the companion question.
Magpul PMAG 30 GEN M3 (5.56, 30-round)
This is the magazine the whole fight is about: the standard 30-rounder that feeds nearly every AR in the country. Stupid simple, battle-tested, and about the price of lunch.
What to watch: Nothing forces the justices’ hand. They can grant Duncan, hold it for the rifle ruling, or keep relisting it into the sunset. But an open split between two en banc circuits is the textbook reason the Court takes cases (its own Rule 10 lists a conflict among the circuits first), and the fall calendar already has the rifle cases on it.
For now, a 30-round magazine is an arm in Philadelphia and an accoutrement in San Francisco. The Supreme Court gets to pick which century’s vocabulary controls.
Does the Court take Duncan this fall? Call your shot in the comments.
While the courts argue over what feeds the rifle, our tested picks for the rifle itself live in the Best AR-15s guide.
Sources: Third Circuit en banc opinion, Association of New Jersey Rifle and Pistol Clubs v. Attorney General New Jersey (PDF); Ninth Circuit en banc opinion, Duncan v. Bonta (PDF); Supreme Court dockets 25-198 and 25-153; Second Amendment Foundation, cert-grant announcement.
Justin Trump is the managing editor and owner of CAT Outdoors. The son of a Vietnam veteran, he’s a Certified Glock Armorer, an avid gun enthusiast and 2A advocate. He holds two firearm patents for the CAT M4 and Talon tools. When not managing CAT Outdoors, he enjoys spending time with his family and friends, rooting for Michigan sports teams, and serving his church.