The Ninth Circuit’s reading of the term “arms” is flawed, unjustifiably excluding firearm components from the protections of the people’s right to bear arms.
United States v. DeBorba, issued on June 3, stands as the latest Ninth Circuit ruling aimed at narrowing the scope of protection by treating firearm components as outside the concept of “arms” protected by the Second Amendment. The court asserted that “optional accessories” to firearms—such as slings, scopes, and especially silencers—do not fall within the Amendment’s plain text because they are merely accoutrements rather than weapons. The criterion for inclusion in “arms” purportedly rests on whether the item is essential to the weapon’s normal operation. The meaning of “ordinary” is described as whatever the court chooses.
That conclusion stems from the Ninth Circuit’s 2025 en banc ruling in Duncan v. Becerra, which asserted that a magazine of ten rounds or fewer is required to operate a semi-automatic firearm and is therefore protected, whereas a magazine with more than ten rounds is deemed unnecessary and thus unprotected. For the grounds of this reasoning, see my prior discussion here.
Unsurprisingly, the DeBorba court applied this same method to suppressors; but what about slings and scopes? It appears the court may be signaling a pathway for California lawmakers to prohibit “assault slings” and “assassin scopes.” After all, slings can be used in an off-hand stance to improve accuracy, as is common at shooting matches. That improvement could also plausibly make rapid-fire control more feasible. And although scopes are used for hunting, they are often portrayed as inherently “military-style” in popular culture—such as in the film American Sniper—potentially making them applicable to violent acts.
Setting aside the implausible implications, slings and scopes belong within the broader notion of “arms” since they are integral components used with firearms. Bruen established that the general definition of “arms” encompasses contemporary devices that assist in armed self-defense. The Court used the term “facilitate,” not merely being essential for a shot to go off. Consequently, any features that enhance or influence a firearm’s operation—even when labeled as so-called “accoutrements”—should be treated as part of the protected arms.
The Militia Act of May 8, 1792 required a citizen to equip themselves with a reliable musket or firelock, a sufficient bayonet and belt, two spare flints, plus a knapsack and a pouch containing not less than twenty-four cartridges. The statute referred to “the arms, ammunition and accoutrements, required as aforesaid.” Taken together, these items were considered “arms.” A musket would not fire without a flint, even though Duncan labeled flints as accoutrements rather than arms. And ammunition is essential to discharge a shot. The use of the term “accoutrements” did not imply an exclusion from Second Amendment protection.
Turning to the DeBorba case, which concerned an unregistered suppressor, it is notable that the Gun Control Act defines “firearm” to include a “firearm silencer or firearm muffler.” In DeBorba, when ATF affixed DeBorba’s device to a portable firearm and discharged it, the device reduced the sound by at least twelve decibels. In Bruen’s framework, that device qualifies as an instrument capable of “facilitating” armed self-defense.
The circuit’s criterion posits that any item the legislature might prohibit that is not strictly required for the gun to discharge falls outside “arms” as a mere accessory. If a scope qualifies, then ordinary sights would as well. This aligns with a persistent antigun argument: enhancements that improve accuracy or ease of use—such as a pistol grip or an adjustable stock—render a firearm disproportionately dangerous and therefore potentially ban-worthy. By that logic, a firearm could be left with only its barrel and firing mechanism and still discharge a shot, meaning only those bare components would remain protected by the Second Amendment.
Even if suppressors are protected by the Second Amendment, DeBorba notes, Bruen’s footnote 9 introduces a presumption of constitutionality for permitting regimes that do not require applicants to demonstrate an unusual need for armed self-defense, and that operate under narrow, objective standards guiding licensing officials. The NFA functions as a shall-issue framework wherein an applicant submits a written application with fingerprints and a photo and then waits for ATF to register the suppressor.
However, footnote 9 concerns carry-permit schemes rather than mere possession authorizations like the NFA. Licensing asks whether a person should be barred from possessing arms, whereas registration monitors who owns which firearms. There is no universal historical consensus that mere ownership warrants lifelong government registration, including fingerprints, photos, and addresses. Public carrying has long been legally distinguished from home possession. Regardless of historical justifications for shall-issue regimes, there are no historical analogs for NFA-type restrictions as applied to private arm possession.
In Heller II (D.C. Cir. 2011), witnesses for the District acknowledged that the registration scheme had not produced any solved crimes. In his dissent, then-Judge Brett Kavanaugh warned that the asserted rationale for registration—allowing police to know whether residents possess guns—amounted to a weak, Swiss-cheese justification that yields too many false negatives to satisfy strict or intermediate scrutiny of a fundamental right.
The Ninth Circuit’s tendency to strip away protections by narrowing what counts as “arms” mirrors the pre-Heller era, when some courts were quick to treat certain individuals as outside the Second Amendment by focusing on the person’s status rather than the principle itself. DeBorba’s actual offenses—violations of restraining orders, being an undocumented immigrant, and misrepresenting information on firearms forms—occurred while he possessed firearms improperly. The court’s approach to those issues does not raise constitutional concerns, and constructing tests that curtail the rights of law-abiding people undermines the Constitution.
