United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Filed May 2, 2023

No. 21-5045

DAMIEN GUEDES, ET AL.,

APPELLANTS

FIREARMS POLICY COALITION, INC.,

APPELLEE

v.

BUREAU OF ALCOHOL, TOBACCO, FIREARMS AND

EXPLOSIVES, ET AL.,

APPELLEES

Appeal from the United States District Court

for the District of Columbia

(No. 1:18-cv-02988)

On Petition for Rehearing En Banc

Before: SRINIVASAN, Chief Judge; HENDERSON***,

MILLETT**, PILLARD, WILKINS**, KATSAS*, RAO*,

WALKER****, CHILDS, and PAN*, Circuit Judges

O R D E R
2

Appellants’ petition for rehearing en banc and the

response thereto were circulated to the full court, and a vote

was requested. Thereafter, a majority of the judges eligible to

participate did not vote in favor of the petition. Upon

consideration of the foregoing, it is

ORDERED that the petition be denied.

Per Curiam

FOR THE COURT:

Mark J. Langer, Clerk

BY: /s/

Daniel J. Reidy

Deputy Clerk

* Circuit Judges Katsas, Rao, and Pan did not participate in

this matter.

** A statement by Circuit Judge Wilkins, joined by Circuit

Judge Millett, concurring in the denial of rehearing en banc, is

attached.

*** Circuit Judge Henderson would grant the petition for

rehearing en banc. A statement by Circuit Judge Henderson,

dissenting from the denial of rehearing en banc, is attached. 

**** Circuit Judge Walker would grant the petition for

rehearing en banc. A statement by Circuit Judge Walker,

dissenting from the denial of rehearing en banc, is attached.
WILKINS, Circuit Judge, with whom MILLETT, Circuit

Judge, joins, concurring in the denial of the petition for

rehearing en banc: Petitioners raised two arguments as reasons

of “exceptional importance” for granting the petition, see Fed.

R. App. P. 35(a)(2), namely (1) whether the interpretation of

the statutory terms defining a “machine gun” to include bump

stocks by the Bureau of Alcohol, Tobacco, Firearms, and

Explosives (“ATF” or the “Bureau”) is the best reading of the

statute, and (2) whether the purported ambiguity in the

statutory definition compels an interpretation in their favor

pursuant to the rule of lenity. The panel opinion thoroughly

addressed both arguments, see Guedes v. Bureau of Alcohol,

Tobacco, Firearms & Explosives, 45 F.4th 306 (D.C. Cir.

2022), and neither merit further review by our court. 

I write only to clarify a couple of matters and to respond

to some of the points made in the rehearing petition and by my

dissenting colleagues.

I.

First, I must address some misconceptions about the

legislative and regulatory history.

“Representing the first major federal attempt to regulate

firearms, the [National Firearms Act of 1934] concentrated on

particularly dangerous weapons and devices such as machine

guns, sawedoff shotguns and silencers.” Lomont v. O’Neill,

285 F.3d 9, 11 (D.C. Cir. 2002). See Pub. L. No. 73-474, 48

Stat. 1236 (1934). As originally conceived, the Act and its

implementing regulations did not ban the possession of

machine guns outright; instead, they required a person seeking

to obtain a machine gun to file an application with the Treasury

Department, pay a hefty transfer tax, and submit a photograph,

fingerprints, and a certificate from a local law enforcement

official attesting their belief that the person intended to use the

firearm for lawful purposes. Lomont, 285 F.3d at 11–12. If the
2

Treasury Department granted the application, the person’s

name and address, along with the serial number of the machine

gun, were placed in a registry. Id. The Act made the

manufacture, transfer, or possession of a machine gun without

Treasury approval and payment of applicable taxes unlawful. 

See 26 U.S.C. § 5861. In 1986, Congress prohibited the

transfer or possession of machine guns, except by authorized

military or governmental officials, unless the person lawfully

possessed the machine gun prior to May 19, 1986. See Act of

May 19, 1986, Pub. L. No. 99-308, § 102, 100 Stat. 449 (1986);

see also 18 U.S.C. § 922(o).

As drafted in 1934, the National Firearms Act defined a

“machine gun” as follows:

The term “machine gun” means any weapon

which shoots, or is designed to shoot,

automatically or semiautomatically, more than

one shot, without manual reloading, by a single

function of the trigger.1

1 As my dissenting colleagues point out, see Walker Op. 2 n.1;

Guedes v. Bureau of Alcohol, Tobacco, Firearms & Explosives, 920

F.3d 1, 44–45 (D.C. Cir. 2019) (Henderson, J., concurring in part and

dissenting in part), Congress amended the definition of machine gun

in 1968. The amendment deleted the words “or semiautomatically”

from the above-quoted sentence. Pub. L. No. 90-618, 82 Stat. 1213,

1231 (1968). The 1968 Act also added a second sentence specifying

that “the frame or receiver” of the weapon, or “any combination of

parts designed and intended” to convert a weapon into a machine gun

or to assemble a machine gun, also qualified as a machine gun. Id.

The legislative history clearly indicates that Congress did not

consider the deletion of “or semiautomatically” to be a substantive

change, because Congress stated “[t]his subsection defines the term

‘machinegun’ and the first sentence is existing law.” S. Rep. No. 90-

1501, at 45 (1968) (section-by-section analysis of the bill); see also
3

Pub. L. No. 73-474, § 1(b), 48 Stat. 1236, 1236 (1934). 

Petitioners and my dissenting colleague complain that the

panel’s conclusion that “a ‘single function of the trigger’ is best

understood as a ‘single pull of the trigger’ and ‘analogous

motions’” is somehow novel. Pet. at 11 (quoting Guedes, 45

F.4th at 315, 317); Walker Op. 6–7. Not so. 

Both the Senate and House reports on the National

Firearms Act explained that the bill “contains the usual

definition of machine gun as a weapon designed to shoot more

than one shot without reloading and by a single pull of the

trigger.” S. Rep. No. 73-1444, at 2 (1934) (quoting H.R. Rep.

No. 73-1780 (1934)) (emphasis added). Immediately

following the Act’s passage, the Treasury Department

published a letter ruling defining a machine gun as “a

semiautomatic pistol or an autoloading pistol when converted

into a weapon which shoots automatically, that is, one capable

of discharging the entire capacity of its magazine with one pull

of the trigger. . . .” Rev. Rul. XIII-38-7035, S.T. 772, 13-2

C.B. 433–34 (Jul.-Dec. 1934) (emphasis added).2

 Thus,

Federal Firearms Legislation, Hearings before the Senate Judiciary

Committee, Juvenile Delinquency Subcommittee, 90th Cong. 135

(1968) (quoting from section-by-section analysis submitted to

Congress by Hon. Sheldon S. Cohen, Commissioner of Internal

Revenue) (“This subsection defines the term ‘machine gun’ and the

first sentence is existing law.”). Accordingly, attempts to rely upon

the 1968 deletion of “or semiautomatically” to narrow the reach of

the text, see Pet. at 12; Walker Op. 8–9; Guedes, 920 F.3d at 44–45

(Henderson, J., concurring in part and dissenting in part), are without

merit.

2 This 1934 letter ruling was not cited in the briefing or in the panel

opinion. I found it when performing subsequent research after the

rehearing petition was filed.
4

“single function of the trigger” was construed as equivalent to

“single pull” of the trigger at the outset. 

Significantly, the 1934 Treasury letter ruling defines

machine gun consistent with how a bump stock operates,

because it is a device that is “capable of discharging the entire

capacity of its magazine with one pull of the trigger.” 13-2

C.B. at 434. As the District Court found, “[o]nce the shooter

pulls the trigger, a bump stock harnesses and directs the

firearm’s recoil energy, thereby forcing the firearm to shift

back and forth, each time ‘bumping’ the shooters stationary

trigger finger. The shooter is thus able to reengage the trigger

without additional pulls of the trigger.” Guedes v. Bureau of

Alcohol, Tobacco, Firearms, & Explosives, 520 F. Supp. 3d 51,

58 (D.D.C. 2021) (emphasis added). Petitioners did not

properly challenge the predicate for these factual findings when

proposed by the government at the summary judgment stage,

and they did not challenge the District Court’s factual findings

as clearly erroneous on appeal. See Guedes, 45 F.4th at 317–

18. Petitioners’ attempt to wriggle out of these findings at the

rehearing stage, see Pet. at 10 n.2, comes way too late and is at

least doubly forfeited.

I refer to this 1934 letter ruling not because its

interpretation is binding upon or must be deferred to by this

Court. Instead, it bears mention because it refutes Petitioners’

contention that the 2018 bump stock rule “contradicts eight

decades of interpretations by the Treasury Department and the

ATF.” Pet. at 15; see also Guedes, 920 F.3d at 46–47

(Henderson, J., concurring in part and dissenting in part). To

the extent the relative gravitas of the various letter rulings is

relevant to the debate, I note that the 1934 letter ruling was

public, issued by the Acting Commissioner of Internal

Revenue, and approved by the Secretary of the Treasury, see

13-2 C.B. at 440, whereas the bump stock letter rulings issued
5

between 2008 and 2017 cited by Petitioners and the dissent

were all private, rather than public, and issued by subordinate

Bureau officials, see Administrative Record (“A.R.”) 424–84. 

See 26 C.F.R. § 601.601(d)(2)(v)(d) (“Revenue Rulings

published in the Bulletin do not have the force and effect of

[regulations], but are published to provide precedents to be

used in the disposition of other cases, and may be cited and

relied upon for that purpose. No unpublished ruling or decision

will be relied on, used, or cited, by any officer or employee of

the Service as a precedent in the disposition of other cases.”). 

Further, the suggestion by Petitioners and the dissent that

purchasers of bump stocks were entitled to rely on the 2008-

2017 private letter rulings is wholly without merit. See id.; see

also McCutchen v. United States, 14 F.4th 1355, 1368–70 (Fed.

Cir. 2021), cert. denied, 143 S. Ct. 422 (2022) (holding that

bump stock private letter rulings did not establish a property

right because the Bureau’s handbook, “which is public, states

that a [firearm] classification provided by letter is ‘subject to

change if later determined to be erroneous,’” and also because

the letter rulings were informal, unpublished, and not issued

through rulemaking); Hanover Bank v. Comm’r, 369 U.S. 672,

686 (1962) (“[P]etitioners are not entitled to rely upon

unpublished private rulings which were not issued specifically

to them[.]”).

Relatedly, the dissent’s characterization of the 2018 Rule

as Executive overreach ignores the constitutional and statutory

context and exaggerates what happened here. Walker Op. 1,

10–16. As we have previously held, Congress explicitly gave

the Secretary of Treasury “interpretative rulemaking power” in

the National Firearms Act. See Lomont, 285 F.3d at 16 (citing

26 U.S.C. § 7805(a)). Thus, the statute, and the Executive’s

power to “take Care that the Laws be faithfully executed,” U.S.

CONST. art. II, § 3, made it perfectly appropriate for the Bureau

to issue a rule explaining what it believed the statute meant and
6

how it would enforce the law going forward. The 2018 Rule

was not an extraconstitutional “power grab[],” Walker Op. 1,

but rather a fitting response to many reasonable questions about

the Executive’s view of the scope of the statutory machine gun

prohibition and how it would be enforced following a national

tragedy. And while the Executive can pronounce its statutory

interpretation consistent with the constitutional order, the

judicial branch has the power and responsibility to render the

authoritative interpretation of the statute. There is no

constitutional crisis.

II.

As the panel explained, “a ‘single function’ of the trigger

is best understood as a ‘single pull of the trigger’ and

‘analogous motions,’ while automatically is best understood to

mean a ‘result of a self-acting or self-regulating mechanism.’” 

Guedes, 45 F.4th at 317. I will let the panel opinion speak for

itself. I add only that the 1934 letter ruling, issued by the

Commissioner and adopted by the Secretary, is consistent with

the panel’s interpretation, and thus corroborates that the panel

interpretation is the best reading of the statute. 

As the 1934 Cumulative Bulletin indicates, none other

than Robert H. Jackson—as Assistant General Counsel of the

Bureau of Internal Revenue—authored over two dozen

regulations, letter rulings, and opinion letters that were

published contemporaneously with the 1934 machine gun letter

ruling. 13-2 C.B., passim. We do not know whether then-Mr.

Jackson drafted or approved the 1934 machine gun letter

ruling, though it is probable. But we do know that, a few years

later, then-Justice Jackson warned that “if the Court does not

temper its doctrinaire logic with a little practical wisdom, it will

convert the constitutional Bill of Rights into a suicide pact.” 

Terminiello v. City of Chicago, 337 U.S. 1, 37 (1949) (Jackson,
7

J., dissenting). The 58 people killed and approximately 500

wounded in Las Vegas by a shooter using bump stock devices

behoove us to heed Justice Jackson’s prescient admonition. 

Where we can employ tools of statutory interpretation to derive

a reasonable interpretation of the statute, we should not find a

“grievous ambiguity” to rule in Petitioners’ favor pursuant to

the rule of lenity. Maracich v. Spears, 570 U.S. 48, 76 (2013). 

One of the manufacturers of bump stocks bragged on its

website, “Did you know that you can do full-auto firing and it

is absolutely legal?” A.R. 840. We do not have to “guess as to

what Congress intended,” Maracich, 570 U.S. at 76, to

determine whether text prohibiting “any weapon which shoots

. . . automatically more than one shot, without manual

reloading, by a single function of the trigger,” 26 U.S.C. §

5845(b), covers a device that concededly replicates “full-auto

firing,” A.R. 840. “There is no war between the Constitution

and common sense.” Mapp v. Ohio, 367 U.S. 643, 657 (1961).

The petition for rehearing en banc is properly denied.
KAREN LECRAFT HENDERSON, Circuit Judge, dissenting 

from the denial of rehearing en banc: For the reasons explained

at the preliminary injunction stage in my separate panel 

opinion, which is hereby incorporated by reference thereto, 

Guedes v. ATF, 920 F.3d 1, 35–49 (D.C. Cir. 2019) 

(Henderson, J., concurring in part and dissenting in part), I 

dissent from the denial of rehearing en banc. And I echo Judge 

Walker’s view that the case presents “question[s] of 

exceptional importance.” D.C. Cir. R. 35(a)(2); see infra at 11–

16 (Walker, J., dissenting from denial of rehearing en banc).
WALKER, Circuit Judge, dissenting from the denial of 

rehearing en banc: Congress recently considered at least five 

bills restricting or banning bump stocks. None passed. Yet 

bump stocks are illegal anyway. That’s because the Bureau of 

Alcohol Tobacco, Firearms, and Explosives stepped into 

Congress’s shoes and criminalized owning a bump stock. 

Like other power grabs by impatient agencies, the Bureau 

decided Congress was taking too long. So it relied on a 

misguided reading of an old statute to solve the problem itself. 

According to the agency, that old statute had banned bump 

stocks all along. 

The Bureau’s overreach is troubling because it turns lawabiding Americans into criminals. Before the Bureau issued its 

rule, it spent a decade telling the public that bump stocks were 

legal. After the rule, bump-stock owners who relied on that 

advice are felons if they do not discard their devices. 

Congress makes the laws — especially the criminal laws. 

The executive branch does not. To reestablish that principle, I 

would grant rehearing en banc. 

I 

Relying on a strained reading of an old statute, the Bureau

banned bump stocks. But no statute gives it that authority. 

A 

The Firearms Owners’ Protection Act of 1986 “effectively 

banned private ownership of machine guns.” Guedes v. ATF, 

920 F.3d 1, 35 (D.C. Cir. 2019) (Guedes I) (Henderson, J., 

concurring in part and dissenting in part) (citing Pub. L. No. 

99-308, 100 Stat. 449). The Act made it a crime to “transfer or 

possess a machinegun” that was not “lawfully possessed” 

before 1986. 18 U.S.C. § 922(o)(1), (2)(B). To define
2

“machinegun,” the Act drew on a long-standing definition in 

the National Firearms Act of 1934, as amended in 1968: a 

“machinegun” is a “weapon which shoots . . . automatically 

more than one shot . . . by a single function of the trigger.” 26 

U.S.C. § 5845(b).1

For decades, the government interpreted that definition to 

exclude guns that fire only a single bullet each time the trigger 

moves. In 1955, for instance, the government said that a crankoperated gatling gun was not a machinegun because it was “not 

designed to shoot automatically . . . more than one shot with a 

single function of the trigger.” Rev. Rul. 55-528, 1955 WL 

9410. The crank just let the user fire the gun more quickly. 

Fast forward to 2008. The Bureau relied on similar 

reasoning to find that a bump stock did not turn a 

semiautomatic gun into a machinegun. A bump stock replaces 

the standard stock of a semiautomatic rifle. When a shooter 

fires the rifle, it naturally recoils backwards into the shooter’s 

shoulder. The bump stock captures that recoil energy, 

returning the rifle forward. When that happens, the trigger 

bumps into the shooter’s stationary trigger finger, firing the 

weapon. The rifle will keep firing as long as the shooter keeps 

forward pressure on the bump stock. In “ten letter rulings 

between 2008 and 2017,” the Bureau said “bump-stock-type 

devices” did not “qualify as machineguns” because they do not 

work “automatically.” 83 Fed. Reg. 66,514, 66,517 (Dec. 26, 

2018). Instead, they require “the maintenance of pressure by 

the shooter” to work. Id. at 66,518. 

1 The Act originally defined a machinegun as “any weapon which 

shoots, or is designed to shoot, automatically or semiautomatically,

more than one shot.” Pub. L. No. 73-474, 48 Stat. 1236 (emphasis 

added). The Gun Control Act of 1968 deleted the words “or 

semiautomatically.” Pub. L. No. 90-618, 82 Stat. 1231. 
3

Then in 2017, a gunman using a bump stock killed 58 

people and wounded 500 others in Las Vegas. In the wake of 

that tragedy, Congress considered legislation to ban or restrict 

bump stocks. See, e.g., H.R. 4168, 115th Cong. (2017); S. 

1916, 115th Cong. (2017); S. 2475, 115th Cong. (2018); H.R. 

4594, 116th Cong (2019); H.R. 5427, 117th Cong. (2021). Yet 

for better or worse, those bills did not become laws. 

In our system of separated powers, that should have been 

the end of the story. Congress alone makes the laws. U.S. 

Const., Art. I. And Congress has not yet decided to ban bump 

stocks. If that is bad policy, Americans can show their 

disapproval at the ballot box by voting out their representatives. 

But instead of letting the democratic process play out, the 

Bureau took matters into its own hands. While legislative 

efforts were ongoing, the Bureau issued a rule reinterpreting 

the statutory definition of “machinegun” to include bump 

stocks. 83 Fed. Reg. at 66,514. In doing so the Bureau 

reversed the interpretation of the statute it had stuck to for a 

decade. Id. at 66,517. 

The Bureau also went further than some of the proposals 

Congress rejected. For instance, the proposed Closing the 

Bump-Stock Loophole Act would have required bump-stock 

owners to “register” their devices with the Bureau. H.R. 4168, 

115th Cong. (2017). The Bureau eschewed all such half 

measures; its reinterpretation of the statute banned bump stocks 

altogether.

After the Bureau’s interpretive about-face, Damien Guedes 

and several other plaintiffs brought a challenge under the 

Administrative Procedure Act. See Guedes v. Bureau of 

Alcohol, Tobacco, Firearms, & Explosives, 520 F. Supp. 3d 51

(D.D.C. 2021). Guedes argued that the Bureau lacked statutory 
4

authority to ban bump stocks because they are not covered by 

the National Firearms Act’s definition of “machinegun.” Id. at 

61. The district court rejected that argument and a panel of this 

court affirmed. Guedes v. Bureau of Alcohol, Tobacco, 

Firearms & Explosives, 45 F.4th 306, 317 (D.C. Cir. 2022)

(Guedes II). Guedes now petitions for rehearing en banc.

B

The Bureau’s rule misreads the National Firearms Act.

Under the Act, a “machinegun” must “shoot[] . . . 

automatically more than one shot . . . by a single function of 

the trigger.” 26 U.S.C. § 5845(b). A bump stock neither lets a 

shooter “automatically [fire] more than one shot” nor lets him 

do so by “a single function of the trigger.” Id. So Congress’s 

ban on machineguns unambiguously does not cover them. 

1

Start with the phrase “single function of the trigger.”

In 1934, when the statutory definition of “machinegun” 

became law, “function” meant the “natural and proper action” 

of a thing. Webster’s New International Dictionary 876 (2d ed. 

1933). Something’s “function” was “[t]he special kind of 

activity proper to [it]; the mode of action by which it fulfills its 

purpose.” 4 Oxford English Dictionary 602 (1933); see also 

Wisconsin Central Ltd. v. United States, 138 S. Ct. 2067, 2070 

(2018) (courts should “interpret the words consistent with their 

ordinary meaning at the time Congress enacted the statute”

(cleaned up)).

So here, we must ask whether the “natural and proper 

action” of the trigger lets a rifle modified by a bump stock fire 

“more than one shot.” 26 U.S.C. § 5845(b). It does not. When 
5

shooting with a bump stock, only one shot fires each time the 

trigger moves. See Guedes II, 45 F.4th at 320 (“a bump stock 

device[] fires only one round with each mechanical movement 

of the trigger”). “The trigger . . . must necessarily ‘pull’ 

backwards and release the rifle’s hammer . . . every time that 

the rifle discharges . . . . The rifle cannot fire a second round 

until both the trigger and hammer reset.” Aposhian v. Barr, 

958 F.3d 969, 995 (10th Cir.) (Carson, J., dissenting). Every 

shot requires a new movement of the trigger. If a gun fitted 

with a bump stock fires more than one round with a single 

movement of the trigger, it has malfunctioned.

The Bureau avoids that conclusion by rewriting “single 

function of the trigger” as “single pull of the trigger.” 83 Fed. 

Reg. at 66,514, 66,518. Because a shooter firing with a bump 

stock need pull the trigger only once to start firing, the Bureau 

says that a bump stock counts as a machinegun under the 

statute. Id. at 66,514. After that initial pull, the bump stock 

repeatedly pushes the trigger into the shooter’s stationary 

finger, firing additional shots. No additional pulls are required. 

But the Bureau provides scant evidence to support its edit 

of the statute. Relying on a footnote from Staples v. United 

States, 511 U.S. 600, 602 n.1 (1994), and a snippet of testimony 

from a congressional hearing, the Bureau claims that its 

interpretation is “consonant with the statute and its legislative 

history.” 83 Fed. Reg. at 66,518 (quoting Akins v. United 

States, 312 F. App’x 197, 200 (11th Cir. 2009)). 

That is a flimsy foundation for reading the word “function” 

to mean something different. True, in Staples, the Supreme 

Court described an automatic weapon as one that “fires 

repeatedly with a single pull of the trigger.” 511 U.S. at 602 

n.1. But it did so in a footnote describing background facts, not 

when definitively interpreting the National Firearms Act. See 
6

United States v. Olofson, 563 F.3d 652, 657 (7th Cir. 2009) (the 

Staples footnote “was providing a glossary for terms frequently 

appearing in the opinion” and not “interpreting a statute”). 

That leaves the agency with a solitary sentence from a 

committee hearing on the 1934 National Firearms Act to 

support its interpretation. There, the National Rifle 

Association’s then-president testified that a machinegun is a 

weapon “capable of firing more than one shot by a single pull 

of the trigger, a single function of the trigger.” 83 Fed. Reg. at 

66,518 (quotation marks omitted). But legislative history is 

notoriously unreliable. The text of the statute controls, not a 

throw-away line cherry-picked from the 170-page record of a 

congressional hearing. See National Firearms Act: Hearings 

Before the Committee on Ways and Means, H.R. 9066, 73rd 

Cong. (1934); see also Epic Systems Corp. v. Lewis, 138 S. Ct. 

1612, 1631 (2018) (warning against “divin[ing] messages from 

congressional commentary”).2

Perhaps realizing that the agency’s argument is weak, the

panel offered a different explanation for why “function” really 

means “pull.” It reasoned that “function” means an “activity; 

doing; [or] performance,” and “the shooter’s pull is the single 

2 To the agency’s evidence, Judge Wilkins’s eagle-eyed research 

adds a 1934 tax ruling. Wilkins Op. 3. There, the Treasury said a 

“semiautomatic” or “autoloading” pistol becomes a “machine gun” 

when converted to “discharg[e] the entire capacity of its magazine 

with one pull of the trigger.” Rev. Rul. XIII-38-7035, S.T. 772, 13-

2 C.B. 433–34 (Jul.-Dec. 1934). True, that ruling is probative of the 

original public meaning of the Act. But tax rulings can be mistaken, 

even when they may have been written by Robert Jackson. Cf. 

Horace, Ars Poetica (“sometimes even good Homer nods off”). And 

here, for the reasons explained above, strong textual clues counsel 

against equating, as the Treasury did, “single function of the trigger” 

with “one pull of the trigger.”
7

‘activity’ or ‘performance’ of the trigger that causes the gun to 

shoot automatically more than one shot.” Guedes II, 45 F.4th 

at 315 (quotation marks omitted). But that focuses on the 

reason why the trigger moves, not, as the statute requires, on 

how often the trigger moves. That gets it backwards. The 

statute is indifferent about why the trigger moves — pull, 

bump, or otherwise — it looks only to how many shots are

fired each time the trigger moves. 

Plus, reading “function” as “pull” ignores the fact that 

Congress knows how to write “single pull of the trigger” when 

it wants to. Indeed, the National Firearms Act’s definition of 

“rifle” uses that phrase. See 26 U.S.C. § 5845(c) (a rifle “fire[s] 

only a single projectile through a rifled bore for each single pull 

of the trigger”); see also 18 U.S.C. § 921(a)(5) (a shotgun 

“fire[s] through a smooth bore either a number of ball shot or a 

single projectile for each single pull of the trigger”). Yet the 

panel’s interpretation of “function” gives no meaning to 

Congress’s decision to use “single function” in one place and 

“single pull” in another. Cf. Antonin Scalia & Bryan Garner, 

Reading Law: The Interpretation of Legal Texts 170 (2012)

(courts should pay attention to meaningful variation in 

statutory language).

Even if the agency is right that “function” means “pull,” it 

is still not clear that the statute covers bump stocks. The agency 

claims, and the panel accepts, that a “pull” of the trigger can 

include other “analogous” ways of “activat[ing] . . . a trigger” 

like a “push, or some other action.” 83 Fed. Reg. at 66,515, 

66,518 n.5; see also Guedes II, 45 F.4th at 311 (the statute 

covers a “single pull of the trigger and analogous motions.”). 

Here, it is undisputed that a bump stock works by bumping the 

trigger into the shooter’s stationary finger, thus firing the 

weapon. So why does that not count as a motion that is 

analogous to a “pull of the trigger”? The agency has no answer.
8

And if a bump is analogous to a pull, then rifles fitted with 

bump stocks are not machineguns under the National Firearms 

Act. Each bump, like each pull, fires one bullet. A single 

action never causes the rifle to fire more than one shot.

2

A bump stock is not a “machinegun” for a second reason. 

A machinegun must “shoot[] automatically more than one 

shot.” 26 U.S.C. § 5845(b) (emphasis added). A bump stock 

does not.

In 1934, “automatically” meant “having a self-acting or 

self-regulating mechanism,” Webster’s New International 

Dictionary 187 (2d ed. 1934), or “[s]elf-acting under the 

conditions fixed for it, going of itself.” 1 Oxford English 

Dictionary 574 (1933). 

A mechanism cannot be self-acting or self-regulating if it 

requires user input to keep working. And a bump stock needs 

constant input from the shooter if a gun is to keep firing. He 

must keep forward pressure on the bump stock for it to work. 

If he does not, the weapon will fire only one shot. So firing 

with a bump stock requires “skill[] and coordination,” as 

explained in comments on the Bureau’s proposed rule. 83 Fed. 

Reg. at 66,531–32. 

Rather than grappling with that inconvenient fact, the 

Bureau largely ignores it. It says that a bump stock lets a 

shooter fire more than one shot automatically because “the 

device harnesses the firearm’s recoil energy in a continuous 

back-and-forth cycle that allows the shooter to attain 

continuous firing after a single pull of the trigger.” Id. at 

66,519. That is true enough. But it does not account for the 

undisputed fact that a shooter must maintain “forward pressure 
9

on the barrel” for a bump stock to let him fire more than one 

shot. Guedes II, 45 F.4th at 318. And tellingly, the Bureau 

reached a different conclusion for years, finding that bump 

stocks require “multiple inputs by the user for each successive 

shot.” Letter from Richard W. Marianos, ATF Assistant 

Director Public and Governmental Affairs, to Rep. Ed 

Perlmutter, at 1–2 (Apr. 16, 2013), https://perma.cc/46VLJ88S. 

Even worse, the agency’s reading of the statute elides an 

important distinction between automatic and semiautomatic 

guns. In 1934, the “difference between an ‘automatic’ and a 

‘semiautomatic’ gun depended on whether the shooter played 

a manual role in the loading and firing process.” Guedes I, 920 

F.3d at 45 (Henderson, J., concurring in part and dissenting in 

part). A semiautomatic gun is one “in which part, but not all, 

of the operations involved in loading and firing are performed 

automatically.” Id. (quoting Webster’s New International 

Dictionary 187 (2d ed. 1934)). By contrast, after the first shot 

is fired, an automatic gun reloads and fires automatically, so 

long as the shooter keeps his finger on the trigger. Id. A gun 

modified by a bump stock works semiautomatically: the 

shooter plays a manual role in the firing process because he 

must keep constant pressure on the bump stock. 

If Congress had wanted to call a semiautomatic weapon a 

machinegun, it could have. In fact, in 1934, it did. Originally, 

the National Firearms Act defined machinegun to cover both 

guns that fire more than one shot “semiautomatically” and 

those that do so “automatically.” Pub. L. No. 73-474, 48 Stat. 

1236. But in 1968, Congress deleted the word 

“semiautomatically” from the statutory definition. Pub. L. No. 

90-618, 82 Stat. 1213. The Bureau’s rule essentially writes it 

back in.
10

3

To make matters worse, the Bureau’s rule has no 

grandfather clause. That means that hundreds of thousands of 

law-abiding Americans who legally bought bump stocks before 

2018 now possess illegal property. What are they to do? 

According to the Bureau, they should “destroy or abandon their

devices.” 83 Fed. Reg. at 66,530. 

That suggestion is startling. For one thing, many bumpstock owners purchased their devices in reliance on the 

Bureau’s assurance that they were not prohibited. See 83 Fed. 

Reg. at 66,517. For another, when Congress passed its ban on 

machineguns in 1986, it grandfathered in “machinegun[s] that 

w[ere] lawfully possessed before” the ban became effective. 

18 U.S.C. § 922(o)(2)(B). It is hard to imagine that a Congress 

that sought to protect lawful gun owners when it passed the ban 

would have sanctioned the Bureau’s subsequent bait and 

switch. 

* * *

To sum up, a gun fitted with a bump stock is not a 

machinegun because it does not automatically fire more than 

one shot each time the trigger moves. 

In reaching that conclusion, I join other judges who have 

persuasively explained why the Act does not ban bump stocks. 

See Cargill v. Garland, 57 F.4th 447 (5th Cir. 2023) (en banc); 

Guedes I, 920 F.3d at 35 (Henderson, J., concurring in part and 

dissenting in part); Gun Owners of America v. Garland, 19 F. 

4th 890, 910 (6th Cir. 2021) (en banc) (Murphy, J., dissenting); 

Aposhian v. Wilkinson, 989 F.3d 890, 896 (10th Cir. 2021) 

(Tymkovich, C.J., dissenting from vacatur of en banc order). 
11 

II

If this were an ordinary case about statutory interpretation, 

I would not call for rehearing en banc, even if I disagreed with 

the panel’s analysis. En banc review is reserved for

“question[s] of exceptional importance.” D.C. Cir. R. 35(a)(2). 

But the bump stock ban is not ordinary. It’s the source of 

a circuit split. It’s the product of an agency’s impatience with 

Congress. And it’s an affront to 800 years of Anglo-American 

legal history restricting the executive’s power to create new 

crimes. 

In short, even in an era of aggressive executive rulemaking, 

the bump stock ban is a bridge too far. 

A 

En banc rehearing is often appropriate when a panel 

opinion conflicts with other circuit-court decisions. Sweet 

Home Chapter of Communities for a Great Oregon v. Babbitt, 

30 F.3d 190, 195 (D.C. Cir. 1994) (Silberman, J., dissenting 

from denial of rehearing en banc) (“[T]he issue would seem of 

sufficient importance, particularly in light of the circuit split.”); 

cf. D.C. Cir. R. 35(b)(1)(B) (litigants should flag circuit splits 

in their en banc petitions).

Here, circuits are split on the best reading of the National 

Firearms Act’s definition of “machinegun.” 

The Fifth and Sixth Circuits have held, as I would, that the 

Act does not let the Bureau ban bump stocks. See Cargill, 57 

F.4th at 447; Hardin v. Bureau of Alcohol, Tobacco, Firearms 

and Explosives, 2023 WL 3065807 (6th Cir. 2023). The Tenth 
12

Circuit upheld the Bureau’s rule, as did this Court. Aposhian, 

958 F.3d at 989; Guedes II, 45 F.4th at 310. 

B

Two further factors weigh in favor of reconsideration en 

banc.

1

The bump-stock ban is a glaring example of an 

increasingly common story:

1. Congress considers a highly controversial solution to a 

modern problem that attracts great public attention. 

2. Despite that attention, Congress does not pass 

legislation addressing it. 

3. The executive then finds within an old statute the power 

to address the problem that Congress did not. 

That is also what happened with student loan forgiveness. 

Compare H.R. 6800, 116th Cong. (2020) with Loan 

Forgiveness Fact Sheet, White House (Aug. 24, 2022). And 

the COVID vaccine mandate. NFIB v. OSHA, 142 S. Ct. 661, 

662 (2022). And the COVID eviction moratorium. Alabama 

Association of Realtors v. HHS, 141 S. Ct. 2485, 2486 (2021). 

And an attempted nationwide shift away from coal-fired power 

stations. West Virginia v. EPA, 142 S. Ct. 2587, 2614 (2022).

And efforts to build a wall at our southern border. See 

Proclamation 9844, 84 Fed. Reg. 4949 (Feb. 15, 2019)

(declaring an emergency at the southern border to get more 

funding than Congress had appropriated). And net neutrality. 

United States Telecom Association v. FCC, 855 F.3d 381, 476 

(D.C. Cir. 2017) (Kavanaugh, J, dissenting from denial of 

rehearing en banc) (“Congress has debated net neutrality for 
13

many years, but Congress has never enacted net neutrality 

legislation or clearly authorized the FCC to impose commoncarrier obligations on Internet service providers.”). 

The point is not that any of those policies is good or bad. 

The point is that the executive branch is acting when Congress 

does not. That intrudes on Congress’s constitutionallyassigned role and disincentivizes it from legislating in the 

future. Why would Congress bear the political costs of passing 

laws when it can let bureaucrats shoulder them instead? See 

Elena Kagan, Presidential Administration, 114 Harv. L. Rev. 

2245, 2255–56 (2001) (Congress sometimes enacts “openended grants of power” in order to “pass on to another body 

politically difficult decisions”). 

I will not rehash here all the reasons why lawmaking by the 

executive is problematic. I’ve written about it before. 

American Lung Association v. EPA, 985 F.3d 914, 996–97 

(D.C. Cir. 2021) (Walker, J. concurring in part and dissenting 

in part), overruled by West Virginia, 142 S. Ct. at 2614. So

have many of our nation’s finest judges and scholars. See, e.g., 

Baldwin v. United States, 140 S. Ct. 690, 691 (2020) (Thomas, 

J., dissenting from denial of certiorari); Steven G. Calabresi et 

al., The Rise and Fall of the Separation of Powers, 106 Nw. L. 

Rev. 527, 545–46 (2012). And Madison before them. The 

Federalist No. 48 (J. Madison). And Montesquieu before him. 

1 Montesquieu, The Spirit of the Laws 151–62 (Thomas Nugent

trans. 1777).

2

The Bureau’s rule turns law-abiding bump-stock owners 

into criminals. But the Anglo-American legal system has long 

restricted the executive branch’s power to create new crimes. 

Crimes are made by legislation, not executive fiat. 
14

That principle has its roots in Magna Carta. After King 

John used “summary process” to “arrest and imprison[]” 

Englishmen on “administrative order[s],” English Barons 

forced him to agree to a new set of limits on his power. J.C. 

Holt, Magna Carta 276 (3d ed. 2015). Chief among those 

limits was a commitment that “[n]o free man shall be arrested 

or imprisoned . . . except by the lawful judgment of his peers 

or by the law of the land.” Magna Carta, Ch. 39 (1215). After 

1215, the King could not punish an Englishman “without the 

application of general rules to the case by a tribunal of [his] 

peers.” Nathan S. Chapman & Michael W. McConnell, Due 

Process as Separation of Powers, 121 Yale L.J. 1672, 1682

(2012). Those “general rules” were the “law of the land,” the 

“standing law that governed all of the King’s subjects in 

England.” Id. No longer could the King impose criminal 

punishment whenever it suited his whims. 

Hard-won by the English Barons, that right was cherished

by the American colonists. It was their inheritance as 

Englishmen. And when they enumerated the limits of a central 

government in their new nation, the founders guaranteed that 

“life, liberty, or property” may not be taken “without due 

process of law.” U.S. Const. Amend. V. 

That means that “our Government [must] proceed . . .

according to written constitutional and statutory provisions . . . 

before depriving someone of life, liberty, or property.” Nelson 

v. Colorado, 581 U.S. 128, 150 n.1 (2017) (Thomas, J., 

dissenting) (quotation marks omitted); see also Pacific Mutual 

Life Insurance Co. v. Haslip, 499 U.S. 1, 28 (1991) (Scalia, J., 

concurring) (noting that the phrase “due process of law” meant 

“law of the land”). In other words, the executive branch may 

prosecute only those criminal offenses that Congress has 

authorized by law. The Due Process Clause “was a separation-
15

of-powers concept designed as a safeguard against unlicensed 

executive action, forbidding only deprivations not authorized 

by legislation or common law.” United States v. Vaello 

Madero, 142 S. Ct. 1539, 1545 (2022) (Thomas, J., concurring)

(quotation marks omitted).

To Magna Carta’s guarantee of due process, the 

Constitution added a second safeguard — an independent 

legislature, beholden in no way to the Executive. Article I’s 

Vesting Clause makes clear that Congress alone has the 

“legislative power.” U.S. Const. Art. I, § 1. 

“Perhaps the most important consequence of th[at] 

assignment concerns the power to punish. Any new national 

laws restricting liberty require the assent of the people’s 

representatives and thus input from the country’s ‘many parts, 

interests and classes.’” Wooden v. United States, 142 S. Ct. 

1063, 1083 (2022) (Gorsuch, J., concurring) (quoting The 

Federalist No. 51 (J. Madison)). Indeed, since 1812, the 

Supreme Court has said that Congress alone defines crimes and 

fixes punishments. United States v. Hudson & Goodwin, 11 

U.S. (7 Cranch) 32, 34 (1812) (“The legislative authority of the 

Union must . . . make an act a crime [and] affix a punishment 

to it.”); see also United States v. Wiltberger, 18 U.S. (5 Wheat.) 

76, 95 (1820) (Marshall, C.J.) (“[T]he power of punishment is 

vested in the legislative . . . department. It is the legislature . . . 

which is to define a crime, and ordain its punishment.”).

Today, those safeguards are not what they used to be. In 

the early 1900s, Congress began to delegate open-ended 

powers to executive agencies. Kagan, supra, at 2255. And by 

the late 1940s, the Supreme Court would uphold any delegation 

if Congress provided an intelligible principle to guide the 

agency. American Power & Light Co. v. SEC, 329 U.S. 90, 

105 (1946); see also J.W. Hampton Jr. & Co. v. United States, 
16

276 U.S. 394, 409 (1928) (coining the “intelligible principle” 

phrase). Under the Supreme Court’s light-touch nondelegation 

doctrine, it has upheld as a valid delegation a statute 

“endow[ing] the nation’s chief prosecutor with the power to 

write his own criminal code governing the lives of a halfmillion citizens.” Gundy v. United States, 139 S. Ct. 2116, 

2131 (2019) (Gorsuch, J., dissenting); cf. Touby v. United 

States, 500 U.S. 160, 165–66 (1991) (it is an open question 

whether “something more than an ‘intelligible principle’ is 

required when Congress authorizes another Branch to 

promulgate regulations that contemplate criminal sanctions”). 

Whatever the merits of that development, one safeguard 

has not loosened. When Congress does delegate rulemaking 

authority, the executive branch must remain faithful to the 

statutory text. It may not use creative interpretations to grab 

for itself even more power. But the Bureau’s rule does just 

that, stretching the text of the National Firearms Act to 

criminalize conduct that Congress has not. 

* * *

The day before the Bureau’s rule, owning a bump stock was 

legal. The day after, it carries a ten-year prison sentence — all 

without Congress lifting a finger. 

I would grant rehearing en banc to reestablish that the 

power to make crimes stays where the Constitution put 

it — with Congress.