Bump Stocks and the Second Amendment

The Supreme Court heard oral argument Wednesday morning in Garland v. Cargill, an administrative law challenge to ATF’s 2018 ban on bump stocks that characterizes those devices as “machineguns” under the National Firearms Act.  For a more comprehensive summary of the issues in the case, see this recent overview by Dru Stevenson.  Cargill made no Second Amendment claim in the case, arguing instead that the unambiguous statutory language of the NFA does not authorize ATF to ban bump stocks.  The Second Amendment came up only once at oral argument, when Justice Kavanaugh questioned Cargill’s attorney Jonathan Mitchell about the decision to omit a Second Amendment claim or constitutional avoidance argument (in other words, an argument that the Court should rule for Cargill because that path avoids the need to separately consider whether ATF’s rule might also implicate the Second Amendment). 

Because the exchange was relatively brief, I’ll reproduce it here in its entirety:

JUSTICE KAVANAUGH: Okay. Last question. You haven’t made a Second Amendment or constitutional avoidance argument. In your view, are bump stocks covered by the Second Amendment, protected by the Second Amendment?

MR. MITCHELL: We didn't argue that because courts are generally loath to decide constitutional questions when there's an easy statutory off-ramp.

JUSTICE KAVANAUGH: You didn’t throw it in as constitutional avoidance, and I imagine that was a considered choice, and I’m curious what -- what was behind that choice.

MR. MITCHELL: There’s nothing that prevents this Court from invoking the constitutional avoidance canon on the Second Amendment issue because there is a question at least whether this falls within the dangerous and unusual weapons carveout in Heller. We don’t have a position on that question because we didn’t brief it, and also "dangerous and unusual weapons" is vague enough that it’s just not clear to us what the answer would be.

While many federal courts have confronted the bump stock issue, the Second Amendment aspect is almost always a sideshow and—as far as I’m aware—no federal court has directly addressed the question of whether bump stocks are protected by the Second Amendment.[1]  I’d like to devote some space here to examining that issue, which isn’t wholly academic. 

In fact, Justice Kavanaugh separately asked Mitchell point blank how Congress should write legislation banning bump stocks,[2] consistent with a major theme among the Court’s conservative justices that the bump stock question should be resolved by the legislative branch.  Such a law, if passed, would not survive for long if courts found the devices protected “arms” and determined there is no analogous historical tradition of regulation.  Approximately 17 states plus DC also currently ban bump stocks under state law, and those laws presumably do not present any of the potential administrative law deficiencies present in Cargill.  These states include a number with current Republican governors and Republican state legislative majorities—Florida, Iowa, Louisiana, and Indiana, to name a few.

The question of whether bump stocks are “arms” protected by the Second Amendment implicates two separate inquiries.  First, if bump stocks are categorized as firearm accessories, are they nevertheless protected by the amendment?  In other words, what kind of accessory parts does the amendment protect in addition to guns themselves?  Courts unanimously agree that certain ancillary items are protected.  For example, as the Ninth Circuit noted in 2014, “without bullets, the right to bear arms would be meaningless.”  Most courts have similarly held that magazines are essential to exercise the right and thus protected; however, as a Rhode Island judge recently observed, “a firearm can fire bullets without a detachable magazine, and in any event, a firearm does not need a magazine containing more than ten rounds.”  Bump stocks, however, seem to have a more tenuous claim to being “arms” as they don’t perform nearly as important a function as bullets or a magazine.  They are perhaps more akin to a stabilizing pistol brace or a silencer: an accessory that might make firing a gun easier or more efficient but is not necessary to use the gun.

This issue has come up in ongoing litigation challenging President Biden’s rule subjecting stabilizing braces to heightened regulation as short-barreled rifles under the GCA (for general background, see this overview by A.W. Geisel).  While most arguments in the pistol-brace litigation are not constitutional arguments but rather sound in administrative law, Fifth Circuit judge Don Willett concurred in an August 2023 decision that issued an injunction against the rule to express his view that “protected Second Amendment ‘conduct’ likely includes making common, safety-improving modifications to otherwise lawfully bearable arms.”  This prompted sharp disagreement from Judge Stephen Higginson who would have held that pistol braces are “dangerous and unusual” and not protected—more on that below.  The district judge in the case subsequently adopted Judge Willett’s view in his preliminary injunction analysis and referenced an ancillary protected right to “to modify or acquire modifications to lawfully bearable firearms so as to increase their accuracy and safety for a more effective exercise of self-defense” (for more on that decision, see our summary here). 

Similar arguments are often made in Second Amendment cases involving silencers.  For example, in a recent case out of North Carolina, a criminal defendant contested his conviction for possessing an unregistered silencer.  He argued that, “because silencers protect users’ ears from firearm's potentially dangerous sound levels and the CDC recommends their use in shooting ranges, . . . . they are ‘reasonably necessary’ such that they receive Second Amendment protection.”  The judge in that case rejected the argument and found that silencers were not “arms” because a “firearm can be used safely and effectively without a silencer.”  And I suspect an analogous argument might be offered with regard to bump stocks; indeed, Mitchell asserted at oral argument that “[b]ump stocks can help people who have disabilities, who have problems with finger dexterity, people who have arthritis in their fingers”—prompting a somewhat incredulous question in response from Justice Sotomayor.  In sum, I think the initial coverage inquiry is probably a close call and that bump stocks may qualify for protection especially under the expansive view articulated recently by some federal judges.  Moreover, courts somewhat frequently assume textual coverage when the question is close.

However, this is not the end of the inquiry.  As Mitchell referenced at oral argument, the question remains whether bump stocks are “dangerous and unusual” under Heller.  If anything, I think the oral argument in Cargill lent more credence to this idea—which is perhaps why Mitchell hedged so much in his response to Justice Kavanaugh (instead of saying, for example, that he was not making the argument but believes that bump stocks are protected).  Here, it’s difficult to follow Heller’s assertion that the Second Amendment does not protect “M-16 rifles and the like” and also find the amendment does protect a device that enables a semiautomatic gun to be fired at nearly the same rate as an M-16 switched to fully-automatic mode.  In other words, it would be a lot harder to make the Second Amendment argument here than the purely textual argument Mitchell offered because, with the latter, Mitchell was free to acknowledge the rate of fire for bump firing but simply state that this is irrelevant under the NFA’s definition of “machinegun” (a sticking point with several of the liberal justices).  In some of the bump stock litigation, certain federal judges embraced the view that bump stocks are “dangerous and unusual” in the sense that their confiscation does not give rise to a claim under the Fifth Amendment’s Takings Clause.  It’s not clear, however, that this view translates directly into the Second Amendment context because the government generally has broad power to take or criminalize possession of property, without compensation to owners, when that action is consistent with the police power to ensure public safety.  

Under the Supreme Court’s Second Amendment jurisprudence, the flip side of “dangerous and unusual” is “in common use for lawful purposes.”  ATF itself estimates that over 500,000 bump stocks were lawfully purchased between 2010 and 2018—which almost certainly puts the number of lawful owners above the 200,000 lawfully owned stun guns that Justice Alito referenced in his Caetano concurrence; but well below the number of semiautomatic weapons subject to state assault weapon bans owned by civilians (by one count, 24.6 million American civilians and counting own “AR-15 or similar styled rifle[s]”).  This aspect seems like a relatively close call, as well, but I believe most courts would ultimately conclude that (if bump stocks are “arms”) they are dangerous and unusual and thus not protected because they enable a rate of fire nearly equivalent to an M-16.

If a court did find that bump stocks are “arms” and in common use for lawful purposes, the next step would be Bruen’s historical test.  This seems quite clearly an instance of unprecedented technological development—the first mechanical bump stock device, the Akins accelerator, was only patented in 2000, and no earlier predecessors were referenced at oral argument or in the briefing in Cargill (indeed, it seemed to be a point of some frustration among the justices that Congress clearly did not have bump stocks, or anything similar, in mind when it drafted the NFA).  It’s also likely more difficult to draw a direct through-line from Founding-era firearm modifications or accessories to bump stocks than it is to stabilizing braces or self-manufactured firearms.  What the government might offer as historical support is unclear—perhaps the historical laws that have been raised in ongoing assault weapons ban litigation, or perhaps historical laws that addressed spring-guns or other modified firearms that may bear at least a passing resemblance to bump fired weapons.  The outcome would turn on how flexibly a court conducts the historical analogical inquiry and whether a historical tradition of responding to new technological developments that make weapons exceptionally dangerous by banning such devices and weapons is sufficient.