Bondi v. Vanderstok

P R E L I M I N A R Y P R I N T
Volume 604 U. S. Part 2
Pages 458–517
OFFICIAL REPORTS
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T H E S U P R E M E C O U R T
March 26, 2025
REBECCA A. WOMELDORF
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458 OCTOBER
TERM, 2024
Syllabus
BONDI, ATTORNEY GENERAL, et al. v.
V
ANDERSTOK et al.
certiorari to the united states court of appeals for
the fth circuit
No. 23–852. Argued October 8, 2024—Decided March 26, 2025
The Gun Control Act of 1968 (GCA) requires those engaged in importing,
manufacturing, or dealing in frearms to obtain federal licenses, keep
sales records, conduct background checks, and mark their products with
serial numbers. The Act defnes “frearm” to include “(A) any weapon
. . . which will or is designed to or may readily be converted to expel a
projectile by the action of an explosive; [and] (B) the frame or receiver
of any such weapon.” 18 U. S. C. § 921(a)(3). Recent years have wit-
nessed profound changes in how guns are made and sold, with companies
now able to sell weapon parts kits that individuals can assemble into
functional frearms at home. These kits vary widely in how complete
they come and in how much work is required to fnish them. Sales
have grown exponentially, with law enforcement agencies reporting a
dramatic increase in untraceable “ghost guns” used in crimes—from
1,600 in 2017 to more than 19,000 in 2021.
In 2022, the Bureau of Alcohol, Tobacco, Firearms and Explosives
(ATF) adopted a rule interpreting the Act to cover weapon parts kits
that are “designed to or may readily be converted to expel a projectile,”
27 CFR § 478.11, and “partially complete, disassembled, or nonfunc-
tional” frames or receivers, § 478.12(c). Before ATF could enforce its
rule, gun manufacturers and others fled what they described as a facial
challenge under the Administrative Procedure Act, arguing that the
GCA cannot be read to reach weapon parts kits or unfnished frames or
receivers. The District Court agreed and vacated the rule. The Fifth
Circuit affrmed, holding that § 921(a)(3)(A) categorically does not reach
weapon parts kits regardless of completeness or ease of assembly, and
that § 921(a)(3)(B) reaches only fnished frames and receivers.
Held: The ATF's rule is not facially inconsistent with the GCA. Pp. 467–
484.
(a) Section 478.11's provisions addressing weapon parts kits are not
facially invalid under § 921(a)(3)(A). That subsection contains two re-
quirements: a “weapon” must be present, and that weapon must be able
to expel a projectile by the action of an explosive, designed to do so, or
susceptible of ready conversion to operate that way. Some weapon
parts kits meet that description. Consider, for instance, Polymer80's
“Buy Build Shoot” kit, which contains all necessary components to build

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459
Syllabus
a semiautomatic pistol and can be assembled in about 20 minutes using
common
tools. That kit qualifes as a “weapon” because: (1) artifact
nouns like “weapon” often describe unfnished objects when their in-
tended function is clear, as with a disassembled rife; (2) the statute
treats starter guns as weapons though they require conversion work;
and (3) the statutory text contemplates that some things short of fully
operable frearms qualify as “weapons.” The kit also satisfes the stat-
ute's second requirement, as it requires no more time, expertise, or spe-
cialized tools to complete than a starter gun, which the statute treats
as readily convertible into a functioning frearm. While other kits may
be so incomplete or cumbersome to assemble that they cannot fairly be
described as weapons capable of ready conversion, the facial challenge
fails because kits like Polymer 80's clearly qualify. Pp. 467–477.
(b) Section 478.12(c)'s treatment of partially complete frames and re-
ceivers is also not facially invalid under § 921(a)(3)(B). Like “weapon,”
the ar ti fac t nouns “frame” and “receiver ” may descr ibe not-yet-
complete objects. The statute uses these terms to encompass some un-
fnished items elsewhere, as in § 923(i)'s serialization requirements for
incomplete weapons, silencers, and destructive devices. ATF has for
decades interpreted the statute to reach some unfnished frames and
receivers, and even the plaintiffs concede they have no “quarrel” with
ATF's prior practice of regulating those products. Accordingly, the
statute authorizes ATF to regulate at least some incomplete frames or
receivers that take minutes of work with common tools to complete.
While other products may be so far from fnished that they cannot fairly
be described as frames or receivers, the facial challenge fails because
the statute plainly reaches some partially complete items. Pp. 477–481.
(c) The plaintiffs' arguments about the linguistic differences between
subsections (A) and (B) and potential unintended consequences under
the National Firearms Act (NFA) are unpersuasive. The government
represents that AR–15 receivers do not qualify as machinegun receiv-
ers, and this Court's analysis of the GCA does not suggest ATF has
authority to regulate them as such under the NFA. Pp. 481–484.
(d) Neither the rule of lenity nor constitutional avoidance applies
where, as here, the statute's text, context, and structure make clear it
reaches some weapon parts kits and unfnished frames or receivers.
P. 484.
86 F. 4th 179, reversed and remanded.
Gorsuch, J., delivered the opinion of the Court, in which Roberts,
C. J., and Sotomayor, Kagan, Kavanaugh, Barrett, and Jackson, JJ.,
joined. Sotomayor, J., post, p. 485, Kavanaugh, J., post, p. 486, and

460 BONDI
v. VANDERSTOK
Syllabus
Jackson, J., post, p. 487, each fled concurring opinions. Thomas, J., post,
p
. 488, and Alito, J., post, p. 513, each fled dissenting opinions.
Solicitor General Prelogar argued the cause for petition-
ers. With her on the briefs were Principal Deputy Assist-
ant Attorney General Boynton, Deputy Solicitor General
Fletcher, Nicole Frazer Reaves, Mark B. Stern, and Sean
R. Janda.
Peter A. Patterson argued the cause for respondents.
With him on the brief for respondent VanDerStok et al. were
David H. Thompson, William V. Bergstrom, Cody J. Wis-
niewski, William E. Trachman, R. Brent Cooper, and Mi-
chael J. Sullivan. Charles R. Flores, Adam Kraut, and
Josh Blackman fled a brief for respondent Defense Distrib-
uted et al.*
*Briefs of amici curiae urging reversal were fled for the District of
Columbia et al. by Brian L. Schwalb, Attorney General of the District
of Columbia, Caroline S. Van Zile, Solicitor General, Ashwin P. Phatak,
Principal Deputy Solicitor General, and Elissa R. Lowenthal, Assistant
Attorney General, by Matthew J. Platkin, Attorney General of New Jer-
sey, Jeremy Feigenbaum, Solicitor General, and Samuel L. Rubinstein,
Deputy Attorney General, by Michelle A. Henry, Attorney General of
Pennsylvania, and Lisa E. Eisenberg, Deputy Attorney General, and by
the Attorneys General for their respective jurisdictions as follows: Kristin
K. Mayes of Arizona, Rob Bonta of California, Philip J. Weiser of Colo-
rado, William Tong of Connecticut, Kathleen Jennings of Delaware, Anne
E. Lopez of Hawaii, Kwame Raoul of Illinois, Aaron M. Frey of Maine,
Anthony G. Brown of Maryland, Andrea J. Campbell of Massachusetts,
Dana Nessel of Michigan, Keith Ellison of Minnesota, Aaron D. Ford of
Nevada, Letitia James of New York, Joshua H. Stein of North Carolina,
Edward E. Manibusan of the Northern Mariana Islands, Ellen F. Rosen-
blum of Oregon, Peter F. Neronha of Rhode Island, Charity R. Clark
of Vermont, Robert W. Ferguson of Washington, and Joshua L. Kaul of
Wisconsin; for the American Medical Association et al. by Michael J. Dell;
for the Constitutional Accountability Center by Elizabeth B. Wydra and
Brianne J. Gorod; for the District Attorney for New York County et al.
by Steven C. Wu, Richard Dearing, and Claude S. Platton; for Global
Action on Gun Violence by Timothy C. Hester and Jonathan E. Lowy; for
Gun Owners for Safety by Robert M. Radick; for Gun Violence Prevention
Groups by Kathleen R. Hartnett, Adam M. Katz, and Patrick J. Hayden;
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461
Opinion of the Court
Justice Gorsuch delivered the opinion of the Court.
F
or decades, the Gun Control Act has regulated the sale
of frearms. This case poses the question whether the Act's
for the Local Government Legal Center et al. by John J. Korzen and
Amanda Karras; for the Major Cities Chiefs Association et al. by Mary
B. McCord, pro se, Rupa Bhattacharyya, and Kelsi Brown Corkran; for
Professors and Scholars of Linguistics and Law by Mark C. Fleming; for
Queens County District Attorney's Offce by John M. Castellano; for
Frank Blackwell et al. by Lee R. Crain, Scott Edelman, and Katherine M.
Marquart; and for 20 Major Cities et al. by Lee S. Richards and Arthur
S. Greenspan.
Briefs of amici curiae urging affrmance were fled for the State of West
Virginia et al. by Patrick Morrisey, Attorney General of West Virginia,
and Michael R. Williams, Solicitor General, by Austin Knudsen, Attor-
ney General of Montana, Christian B. Corrigan, Solicitor General, and
Peter M. Torstensen, Jr., Deputy Solicitor General, and by the Attorneys
General for their respective States as follows: Steve Marshall of Alabama,
Treg Taylor of Alaska, Tim Griffn of Arkansas, Ashley Moody of Florida,
Chris Carr of Georgia, Raúl R. Labrador of Idaho, Theodore E. Rokita of
Indiana, Brenna Bird of Iowa, Kris Kobach of Kansas, Russell Coleman
of Kentucky, Liz Murrill of Louisiana, Lynn Fitch of Mississippi, Andrew
Bailey of Missouri, Michael T. Hilgers of Nebraska, John Formella of
New Hampshire, Drew Wrigley of North Dakota, Dave Yost of Ohio, Gen-
tner Drummond of Oklahoma, Alan Wilson of South Carolina, Marty
Jackley of South Dakota, Jonathan Skrmetti of Tennessee, Ken Paxton
of Texas, Sean Reyes of Utah, Jason Miyares of Virginia, and Bridget
Hill of Wyoming; for the California Gun Rights Foundation by Stephen
M. Duvernay; for the Citizens Committee for the Right to Keep and Bear
Arms et al. by Dan M. Peterson and C. D. Michel; for the Firearms Regu-
latory Accountability Coalition et al. by Stephen J. Obermeier, Jeremy J.
Broggi, and Michael D. Faucette; for the Foundation for Moral Law by
John A. Eidsmoe; for Gun Owners of America, Inc., et al. by John I. Har-
ris III; for the National Association for Gun Rights et al. by David A.
Warrington and Gary M. Lawkowski; for the National Association of
Sporting Goods Wholesalers by Paul D. Clement, Erin E. Murphy, Mat-
thew D. Rowen, and Kevin Wynosky; for the National Rife Association of
America by Joseph G. S. Greenlee and Erin M. Erhardt; for the National
Shooting Sports Foundation, Inc., by H. Christopher Bartolomucci, Ken-
neth A. Klukowski, Stephen P. Halbrook, and Lawrence G. Keane; and for
Rick Vasquez et al. by Bradley A. Benbrook.

462 BONDI
v. VANDERSTOK
Opinion of the Court
longstanding mandates also apply to those who make and sell
a
new product—“weapon parts kits.”
I
A
Shortly after the assassinations of Senator Robert F. Ken-
nedy and Dr. Martin Luther King, Jr. stunned the Nation,
Congress adopted the Gun Control Act of 1968 (GCA). Pub.
L. 90–618, 82 Stat. 1213. Existing gun control measures,
Congress found, allowed criminals to acquire largely un-
traceable guns too easily. See 82 Stat. 225. Often, for ex-
ample, criminals could evade state laws regulating in-person
sales simply by purchasing guns through the mail. Ibid.
In response, Congress adopted a number of new mandates.
As a result, many of those now engaged in importing, manu-
facturing, or dealing in frearms must obtain federal licenses,
keep records of their sales, and conduct background checks
before transferring frearms to private buyers. 18 U. S. C.
§§ 922(t), 923(a), (g)(1)(A). The Act also requires importers
and manufacturers to mark their frearms with serial num-
bers. § 923(i).
These mandates serve at least two ends. The
background-check requirement seeks to keep “guns out of
the hands of criminals. ” Abramski v. United States, 573
U. S. 169, 180 (2014). The licensing, recordkeeping, and seri-
alization requirements, meanwhile, aim “ to assist law en-
forcement authorities in investigating serious crimes,” ibid.,
by per mitting them “ to deter mine where, by whom, or
when” a firearm was manufactured and to whom it was “sold
or other w ise transferred. ” 87 Fed. Reg. 24652 (2022).
Today, thousands of law-enforcement agencies nationwide
depend on the Act's tracing system to link firearms involved
in crimes to their owners. Id., at 24659.
The GCA's mandates apply to “frearm[s].” See §§ 922(t),
923(a), (i). And the law defnes that key term broadly.
Under § 921(a)(3), a “frearm” includes “(A) any weapon (in-
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Opinion of the Court
cluding a starter gun) which will or is designed to or may
readi
ly be converted to expel a projectile by the action of an
explosive; (B) the frame or receiver of any such weapon; (C)
any frearm muffer or frearm silencer; or (D) any destruc-
tive device.” Thanks to this generous defnition, the GCA
has long been understood to reach everything from run-of-
the-mill rifes to novelty umbrella guns. See AFT, Novelty
Guns (June 5, 2015), https://www.atf.gov/firearms/photo-
gallery-0.
Recent years, however, have witnessed profound changes
in how guns are made and sold. When Congress adopted
the GCA in 1968, “the milling equipment, materials needed,
and designs were far too expensive for individuals to make
frearms practically or reliably on their own.” 87 Fed. Reg.
24688. With the introduction of new technologies like 3D
printing and reinforced polymers, that is no longer true.
Today, companies are able to make and sell weapon parts
kits that individuals can assemble into functional frearms in
their own homes. Ibid.
These kits vary widely both in how complete they come
and in how much work is required to fnish them. At one
end of the spectrum, a kit may lack essential parts and “re-
quir[e] substantial effort, specialized expertise, uncommon
equipment, and a signifcant amount of time” before anyone
can fre a shot. Brief for Former Acting Chief of ATF Fire-
arms Technology Branch et al. as Amici Curiae 35. At the
other end, some kits “contain all components necessary” for
“a complete pistol” and can be completed in perhaps half an
hour using commonly avai lable tools. App. to Pet. for
Cert. 236a.
Sales of these kits have grown “exponential[ly].” Brief
for Petitioners 2. Home hobbyists enjoy assembling them.
VanDerStock v. Garland, 86 F. 4th 179, 185 (CA5 2023). But
criminals also fnd them attractive. Id., at 195. That is
largely due to how the kits are sold. Some manufacturers
and dealers take the position that weapon parts kits do not
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464 BONDI
v. VANDERSTOK
Opinion of the Court
qualify as “frearms” subject to the GCA. As a result, they
say
, they are free to sell their products without obtaining a
federal license, conducting background checks, maintaining
sales records, or marking components with serial numbers.
87 Fed. Reg. 24652.
The upshot? “[P]olice departments around the Nation”
have “confronted an explosion of crimes” involving these
“ghost g uns. ” Br ief for Petiti oners 8. In 2017, law-
enforcement agencies submitted about 1,600 ghost guns to
the federal government for tracing. App. to Pet. for Cert.
194a. By 2021, that number jumped to more than 19,000.
Ibid. Efforts to trace the ownership of these weapons, the
government represents, have proven “almost entirely futile.”
Brief for Petitioners 8.
B
In 2022, the Bureau of Alcohol, Tobacco, Firearms and Ex-
plosives adopted a new rule designed to combat the prolifer-
ation of ghost guns. See 87 Fed. Reg. 24652. In doing so,
the agency invoked authority Congress granted it to pre-
scribe “rules and regulations as are necessary to carry out”
the GCA. 18 U. S. C. § 926(a). Two prov isi ons i n the
agency's new rule are of special relevance here.
The frst addresses weapon parts kits directly. Recall
that § 921(a)(3) extends the GCA's mandates to “frearms,” a
term subsection (A) defnes as “any weapon (including a
starter gun) which will or is designed to or may readily be
converted to expel a projectile by the action of an explosive.”
In its new rule, ATF interpreted this language to embrace
weapon parts kits “that [are] designed to or may readily be
completed, assembled, restored, or otherwise converted to
expel a projectile by the action of an explosive.” 27 CFR
§ 478.11 (2023) (defning “frearm”). Those who make or sell
kits that satisfy this test, ATF said, must comply with the
GCA by securing federal licenses, conducting background
checks, keeping sales records, and marking their products
with serial numbers. To decide whether a kit “may readily
be converted” into a working gun, ATF added, it will con-
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sider several factors, including the time, ease, expertise, and
equipment
required to complete a weapon, as well as the
avai labi l ity of other necessary par ts. Ib i d. (defi ni ng
“readily”).
The second relevant aspect of the agency's new rule con-
cerns a key building block of almost any frearm: its frame
or receiver. Under subsection (B) of § 921(a)(3), “the frame
or receiver of any such weapon” covered by subsection (A)
is itself treated as a “frearm.” Effectively, that means a
frame or receiver is, even when sold separately, subject to
the Act's requirements. Presumably, Congress singled out
these components for special treatment because of the spe-
cial role they play in constructing frearms. As the govern-
ment put it in 1968, a frame or receiver is “[t]hat part . . .
which provides housing for the hammer, bolt or breechblock,
and fring mechanism, and which is usually threaded at its
forward portion to receive the barrel.” 33 Fed. Reg. 18558;
accord, 43 Fed. Reg. 13537 (1978) (formerly codifed at 27
CFR § 478.11 (2020)).
In its 2022 rule, ATF sought to expand this defnition.
Now, the agency said, a “frame or receiver” subject to sub-
section (B) of § 921(a)(3), should be understood to encompass
as well “a partially complete, disassembled, or nonfunctional
frame or receiver, including a frame or receiver parts kit,
that is designed to or may readily be completed, assembled,
restored, or otherwise converted to function as a frame or
receiver.” 27 CFR § 478.12(c) (defning “frame or receiver”).
Still, ATF stressed, the Act and its new rule have their lim-
its. They do not apply until an object has “reached a stage
of manufacture where it is clearly identifable as an unfn-
ished component part of a weapon.” Ibid. So, for example,
“a forging, casting, printing, extrusion, unmachined body, or
similar article” does not count. Ibid.
1
1
Besides these changes, ATF's new rule included a number of others.
For instance, where the agency's old regulations defned frames and re-
ceivers as those parts housing all of a frearm's key components, 43 Fed.
Reg. 13537, ATF's new rule redefned those terms to include parts housing
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C
Before
ATF's new rule took effect and ATF could begin
efforts to enforce its new rule, various gun manufacturers,
at-home gunsmiths, and others fled what they described as
a “facial” challenge under the Administrative Procedure Act
(APA). See, e. g., BlackHawk Mfg. Complaint in No. 22–619
(ND Tex., Oct. 20, 2022), ECF Doc. 99, p. 25. They argued
that the GCA cannot be fairly read to reach weapon parts
kits or unfnished frames or receivers. As a result, the
plai nti ffs contended, ATF's reg u lati ons in § 478.11 and
§ 478.12(c) purporting to extend the GCA's mandates to these
products could not be enforced against anyone and had to be
“set aside” as impermissibly issued “in excess of statutory
. . . authority.” 5 U. S. C. § 706.
At summary judgment, the district court agreed with the
plaintiffs and vacated the agency's new rule. VanDerStok
v. Garland, 680 F. Supp. 3d 741, 766 (ND Tex. 2023). On
appeal, the Fifth Circuit largely affrmed. The court ac-
knowledged that subsection (A) of § 921(a)(3) authorizes ATF
to regulate “weapons” that “may readily be converted to
expel a projectile by the action of an explosive.” But, the
court reasoned, that language does not reach weapon parts
kits. Nor does it matter how complete a kit may come or
how easily it may be assembled. As a categorical matter,
the court held, the Act reaches none of them. 86 F. 4th, at
195. The Fifth Circuit offered a similar assessment when it
came to unfnished frames and receivers. Subsection (B) of
§ 921(a)(3) permits the agency to regulate “the frame or re-
ceiver of any such weapon” covered by subsection (A). But,
the court held, those terms do not speak to, and thus do not
allow the agency to regulate, unfnished frames and receiv-
ers, no matter how close to completion they may be. Id., at
190. For these reasons, the court of appeals concluded, the
only some key components, see 27 CFR §§ 478.12(a)(1), (a)(2). But because
the plaintiffs did not challenge that amendment or others in proceedings be-
low, see Brief for Respondent VanDerStok et al. 31, n. 4, we have no occasion
to pass upon them, see Cutter v. Wilkinson, 544 U. S. 709, 718, n. 7 (2005).
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provisions in ATF's new rule addressing weapon parts kits,
§
478.11, and unfnished frames and receivers, § 478.12(c),
were facially inconsistent with GCA and thus had to be “set
aside” consistent with the APA, 86 F. 4th, at 195.
The government sought review in this Court. Our inter-
vention was necessary, the government insisted, because the
court of appeals had “adopted an interpretation of the Act
that would effectively nullify its central provisions” and leave
criminals today nearly as free to obtain “untraceable frearms”
as they were before the Act's adoption in 1968. Pet. for Cert.
28. We agreed to hear the case. 601 U. S. 1161 (2024).
II
As presented to us, this case does not ask us to resolve
whether ATF's new regulations in § 478.11 and § 478.12 may
be lawfully applied to particular weapon parts kits or unfn-
ished frames or receivers. Instead, the plaintiffs have pur-
sued what the lower courts called a “facial” pre-enforcement
challenge to the agency's authority to regulate any weapon
parts kits or unfnished frames or receivers. 680 F. Supp.
3d, at 766; 86 F. 4th, at 186. In a challenge like that, the
government represents, “the possibility that [ATF's regula-
tion] `may be invalid as applied' in some cases `does not mean
that the regulation is facially invalid.' Instead, [the plain-
tiffs'] burden is to show that the Rule itself is inconsistent with
the statute on its face.” Brief for Petitioners 27–28 (quot-
ing INS v. National Center for Immigrants' Rights, Inc., 502
U. S. 183, 188 (1991); citation omitted (addressing a facial chal-
lenge under the Immigration and Nationality Act)). No-
where in either of their briefs before us do the plaintiffs dis-
pute that assessment. Accordingly, we take it as given for
our purposes here.
2
2
The dissents raise a number of questions about what test courts should
apply when a party contends that an agency has acted in excess of its statu-
tory authority in a pre-enforcement challenge under the APA. Post, at
494–496 (opinion of Thomas, J.); post, at 515–516 (opinion of Alito, J.). But
the theories the dissents proceed to advance were not pressed or passed up-
on below, nor did the parties make them before this Court. Cf. post, at 515
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In doing so, we turn frst to the question whether § 478.11's
prov
isions addressing weapon parts kits are inconsistent on
their face with the GCA. The answer turns on subsection
(A) of § 921(a)(3). There, remember, the GCA authorizes
ATF to regulate “any weapon (including a starter gun) which
will or is designed to or may readily be converted to expel a
projectile by the action of an explosive.” Inhering in this
language are two requirements. First, a “weapon” must be
present. Second, that “weapon” must meet one of three cri-
teria: It must be able to expel a projectile by the action of
an explosive, designed to do so, or susceptible of ready con-
version to operate that way. As the Fifth Circuit saw it,
§ 478.11's provisions addressing weapon parts kits are fa-
cially invalid because no weapon parts kit can ever satisfy
the statute's two requirements. We disagree because, to
our eyes, at least some kits will satisfy both.
A
To appreciate why, it helps to work with an example.
Take a weapon parts kit featured prominently in the record
before us: Polymer80's “Buy Build Shoot” kit. It comes
with “all of the necessary components to build” a Glock-
variant semiautomatic pistol. App. to Pet. for Cert. 219a.
And it is so easy to assemble that, in an ATF test, an individ-
ual who had never before encountered the kit was able to
produce a gun from it in 21 minutes using only “common”
tools and instructions found in publicly available YouTube
videos. Id., at 220a. The frst picture below shows the kit;
the second depicts the gun the kit yields.
(opinion of Alito, J.) (suggesting that the Court ask for supplemental
briefng). In these circumstances, we believe the better course is to leave
further analysis of the proper test for another day and address the parties'
dispute as they have chosen to frame it. Nor, on remand, may the parties
seek to inject arguments about the proper test that they did not pursue
here. See Ohio v. Environmental Protection Agency, 603 U. S. 279, 299
(2024) (forfeiture); Sibbald v. United States, 12 Pet. 488, 492 (1838) (law of
the case); contra, post, at 496 (Thomas, J., dissenting).
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Id., at 232a, 238a.

470 BONDI
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Opinion of the Court
Now, assess whether the “Buy Build Shoot” kit meets sub-
sec
tion (A)'s two tests, and start with the question whether
Polymer80's offering qualifes as a “weapon.” When Con-
gress adopted the GCA in 1968, that term meant what it
means today: “an instrument of offensive or defensive com-
bat [such] as a club, sword, gun, or grenade.” Webster's
Third New International Dictionary 2589 (def. 1) (1966); ac-
cord, 1 Concise Oxford Dictionary of Current English 1476
(def. 1) (5th ed. 1964). As a result, ATF's authority under
subsection (A) extends only to instruments of combat, not to
other things like industrial tools or toy guns that may “expel
a projectile by the action of an explosive.” It is a feature of
the statute the agency itself has long acknowledged. See 87
Fed. Reg. 24684.
Plainly, the fnished “Buy Build Shoot” kit is an instrument
of combat. No one would confuse the semiautomatic pistol
pictured above with a tool or a toy. Of course, as sold, the
kit requires some assembly. But a number of considerations
persuade us that, even as sold, the “Buy Build Shoot” kit
qualifes as a “weapon.”
Consider, frst, a feature of ordinary language. The term
“weapon” is an artifact noun—a word for a thing created by
humans. Artifact nouns are typically characterized by an
intended function,” rather than by some “ineffable `natural
essence.' ” S. Grimm & B. Levin, Artifact Nouns: Reference
and Countability, in 2 Proceedings of the Forty-Seventh An-
nual Meeting of the North East Linguistic Society (NELS
47) 55 (2017).
3
Refecting as much, everyday speakers some-
times use artifact nouns to refer to unfnished objects—at
least when their intended function is clear. An author might
invite your opinion on her latest novel, even if she sends you
3
Accord, Brief for Professors and Scholars of Linguistics and Law as
Amici Curiae 6–9; J. Pustejovsky, The Generative Lexicon 97 (1995);
J. Coleman & O. Simchen, “Law,” 9 Legal Theory 1, 20 (2003); T. Parsons,
The Progressive in English, 12 Linguistics in Philosophy 213, 225–226
(1989).
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an unfnished manuscript. A friend might speak of the table
he
just bought at IKEA, even though hours of assembly re-
main ahead of him. In both cases, the artifact noun fts be-
cause the intended function of the unfnished object is obvi-
ous to speaker and listener alike.
The term weapon can work this way, too. Imagine a rife
disassembled for storage, transport, or cleaning. It may
take time to render the rife useful for combat, but its in-
tended function is clear. And, as a matter of every day
speech, that rife is a weapon, whether disassembled or com-
bat ready. In the same way and for the same reason, an
ordinary speaker might well describe the “Buy Build Shoot”
kit as a “weapon.” Yes, perhaps a half hour of work is re-
quired before anyone can fre a shot. But even as sold, the
kit comes with all necessary components, and its intended
function as instrument of combat is obvious. Really, the
kit's name says it all: “Buy Build Shoot.”
Next, consider what the statute itself has to say about the
term “weapon.” Subsection (A) tells us that the term “in-
clud[es] a starter gun.” § 921(a)(3)(A). A starter gun, of
course, normally fres blanks, not bullets, and is usually
found at sporting events, not in combat. See United States
v. Hall, 396 F. 2d 841, 842, n. 2 (CA4 1968). To be sure, a
starter gun can be converted to live fre using a power tool
commonly available at hardware stores. See United States
v. Mullins, 446 F. 3d 750, 755 (CA8 2006). For someone with
no “specialized knowledge,” the process can take “less than
an hour.” Ibid. But, notably, the statute teaches that a
starter gun is a “weapon” before anyone invests that work.
All of which indicates that Congress used that term, as an
ordinary speaker might, to embrace some unfnished instru-
ments of combat like Polymer80's product.
Finally, notice another feature of the statute. If Congress
had wanted to regulate only operable frearms, it could have
simply addressed “weapons” that can “expel a projectile by
the action of an explosive.” But Congress didn't stop there.

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Instead, Congress explained that a “weapon” also qualifes
for
regulation if it is either “designed” to accomplish that
function or capable of being “readily . . . converted” to do so.
§ 921(a)(3)(A). Those latter provisions necessarily contem-
plate that some things short of fully operable frearms will
qualify as “weapons.” And if that is true, it is diffcult to
see how the easy-to-assemble “Buy Build Shoot” kit might
not be among them.
Of course, to implicate the Act, not only must a “weapon”
be present. That weapon must meet one of the just-
recounted conditions. At a minimum, that means a weapon
must be capable of being “readily . . . converted to expel a
projectile by the action of an explosive.” Ibid. As we see
it, the “Buy Build Shoot” kit satisfes that test, too.
Begin with what we can glean about the “ready-conversion”
standard from the statute. We know that Congress's direc-
tion that a starter gun is a “weapon” would be pointless un-
less a starter gun satisfes all subsection (A)'s terms. For
the statute to make sense, then, a starter gun must be able
to fre bullets, designed to do so, or capable of ready conver-
sion to operate that way. Generally, however, a starter gun
meets neither of the frst two conditions, for its barrel is
deliberately blocked. See United States v. 16,179 Molso
Italian .22 Caliber Winlee Derringer Convertible Starter
Guns, 443 F. 2d 463, 465 (CA2 1971). That leaves only one
serious possibility: It must be that a starter gun “can
readily be converted to expel projectiles by the action of an
explosive.”
That turns out to tell us all we need to know about the
statute's “ready conversion” test. As we have seen, a per-
son without any specialized knowledge can convert a starter
gun into a working frearm using everyday tools in less than
an hour. Mullins, 446 F. 3d, at 755. And measured against
that yardstick, the “Buy Build Shoot” kit can be “readily con-
verted” into a frearm too, for it requires no more time, ef-
fort, expertise, or specialized tools to complete. App. to Pet.

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for Cert. 220a. If the one meets the statutory test, so must
the
other.
Admittedly, our reasoning here has its limits. Just be-
cause some kits, like Polymer80's, qualify as “weapons” that
“can readily be converted” into working frearms does not
mean all do. Think of the problem of the heap: Start with
a heap of sand and begin removing grains; at some point, a
heap no longer exists. That problem attends many artifact
nouns. Even when used to capture unfnished products, ar-
tifact nouns generally reach only so far. It would be extrav-
agant to speak of a novel when the author has dashed off
only a few lines. Few would call a pile of unfnished logs
a table. Subsection (A) may present a similar problem.
Weapon parts kits vary widely. See Part I–A, supra. Not
all come as complete as the “Buy Build Shoot” kit. Some,
too, may require more time, expertise, or specialized tools to
fnish. And at some point a kit may be so incomplete or
cumbersome to assemble that it can no longer fairly be de-
scribed as a “weapon” capable of “read[y] . . . conver[sion]”
into a working frearm. § 921(a)(3)(A).
While we recognize the problem, this case does not require
us to untangle exactly how far subsection (A) reaches. The
plaintiffs argue only that § 478.11's provision addressing
weapon parts kits is facially inconsistent with the statute.
The Fifth Circuit adopted the same view after coming to the
unqualifed conclusion that weapon parts kits can never sat-
isfy the statute's two tests. To resolve this case, it is enough
to say those assessments are mistaken. Because at least
some weapon parts kits satisfy both of subsection (A)'s tests,
§ 478.11 is not facially invalid. Future cases may present
other and more diffcult questions about ATF's regulations.
But we take cases as they come and today resolve only the
question posed to us.
B
The plaintiffs dispute little of what we have said. They
admit that artifact nouns sometimes capture unfnished arti-
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cles. Tr. of Oral Arg. 76–77. They recognize that starter
g
uns qualify as “weapons” even though they require work
before they operate as func ti ona l firear ms. Br ief for
Respondent VanDerStok et al. 34. The plaintiffs concede,
too, that disassembled rifes and guns are “weapons” that can
be “readily . . . converted” to live fre because they have “all
the parts necessary” for an ordinary person “to put toget-
her a functioning frearm” in short order. Id., at 37.
Really, the plaintiffs fail only to take the next step and ac-
knowledge that the same might be said of some weapon
parts kits.
Given all that, what do the plaintiffs have to say in support
of the Fifth Circuit's conclusion that subsection (A) reaches
no weapon parts kits? Perhaps their best argument centers
on the fact that other statutes address collections of parts
while this one does not. As the plaintiffs observe, Congress
has elsewhere defned a “destructive device” to embrace
“any combination of parts . . . from which a destructive de-
vice may be readily assembled.” § 921(4)(C). Similarly,
Congress has specifed that the terms “frearm silencer”
and “frearm muffer” encompass “any part” or “combination
of parts” used to “assembl[e] or fabricat[e]” those items.
§ 921(a)(25); see also Federal Firearms Act of 1938, 52 Stat.
1250 (defning “frearm” to include “any part or parts of
such weapon”). Subsection (A), meanwhile, employs none of
those terms. And because Congress has spoken elsewhere
to collections of frearm parts, the plaintiffs insist, we should
infer this statute does not address parts or kits containing
any combinations of them.
The plaintiffs' conclusion, however, does not follow from
their premise. We do not doubt that subsection (A) sweeps
more narrowly than some other statutes. No one thinks it
reaches every piece or part that can be used to produce a
frearm. Recognizing as much, ATF itself acknowledges
that subsection (A) does not allow it to regulate “standalone
triggers, barrels, stocks, or magazines.” Brief for Petition-
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ers 24. Nor, the agency admits, does the statute authorize
it
to regulate “weapon parts writ large,” without regard
to how complete they come or how diffcult they are to as-
semble. Ibid. But the fact that subsection (A) doesn't go
as far as some other statutes does not tell us how far it does
go. Let alone prove that subsection (A) fails, as a categori-
cal matter, to reach any weapon parts kits.
Faced with that problem, the plaintiffs, joined now by the
dissent, try another tack. They object that weapon parts
kits cannot be “weapons” under subsection (A) because they
lack functional frames or receivers. See Brief for Respond-
ent VanDerStok et al. 35; post, at 507–508 (opinion of
Thomas, J.) (advancing a similar argument). That conclu-
sion rests on two premises: (1) that a “weapon” must have a
fully “functional” frame or receiver, and (2) that no “weapon-
parts kit” includes such a part. Post, at 507–508 (opinion of
Thomas, J.). But neither premise is sound. For one, the
statute nowhere says that a “weapon” must have a fully func-
tional frame or receiver—nor is it obvious how we might
derive such a rule from its terms. In fact, as we have seen,
subsection (A) reaches any “weapon” that may “readily be
converted” to live fre. § 921(a)(3)(A). And a gun that is
fully operable, save for a frame missing a single and easily-
added screw, would surely ft that description. See Part II–
A, supra. For another, even if the statute did require a
“weapon” to have a fully functional frame or receiver, some
weapon parts kits may ft that description. Imagine a kit
identical to Polymer80's in all respects, except that it has
a complete frame. Even the plaintiffs would have to ad-
mit that such a kit would count as a “weapon” under sub-
section (A).
Failing all else, the dissent suggests that other criminal
statutes addressing “frearm[s]” prove that weapon parts kits
cannot fall within the statutory defnition of that term. Post,
at 508–509. So, for example, the dissent observes that Con-
gress has penalized the use of “frearm[s]” during and in rela-
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tion to a “crime of violence,” § 924(c), required “frearm[s]”
to
be “unloaded” during transportation, § 926A, and permit-
ted law-enforcement offcers to carry “concealed frearm[s],”
§ 926B. And, the dissent continues, it is “hard to imagine”
how any of those provisions might apply to weapon parts
kits. Post, at 509. As a result, the dissent insists, we
should prefer a reading that limits the term “frearm” to
completely operable guns. Ibid.
This argument suffers at least two problems as well.
First, what the dissent fnds hard to imagine turns out to be
anything but, for various criminal laws addressing frearms
can apply to weapon parts kits. Just consider some of the
laws we have already encountered that require those who
import, manufacturer, or deal in “frearms” to obtain federal
licenses, keep records of their sales, and conduct background
checks. §§ 922(t), 923(a), (g)(1)(A). Plainly, those criminal
laws can be applied sensibly to weapon parts kits. Or, to
take one of the dissent's own examples, a weapon parts kit
might be “possesse[d]” “in furtherance of ” a “crime of vio-
lence” in violation of § 924(c)(1) when an individual accused
of attempted robbery purchases the kit for assembly and use
in an upcoming heist. See Stokeling v. United States, 586
U. S. 73 (2019) (holding that a state robbery statute qualifes
as a crime of violence).
Second, the dissent's complaint is hardly resolved by
adopting its view of the statute. The dissent must acknowl-
edge, for example, that standalone “frame[s] or receiver[s]”
and “silencer[s]” qualify as “frearms,” for the statute tells
us so expressly. § 921(a)(3). Yet, only rarely would some-
one use a standalone “frame or receiver” during a “crime of
violence,” § 924(c), and it may be impossible to “unloa[d]” a
“silencer” during “transportation,” § 926A. So whether one
adopts our interpretation or the dissent's, not every “fre-
arm” will be capable of implicating every criminal law dis-
cussing frearms. It's a fact that, if it proves anything,
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proves only that Congress's defnition of “frearm” is a capa-
ci
ous one indeed.
4
III
That leaves the question whether ATF's new regulation
addressing unfnished frames and receivers, § 478.12(c), is fa-
cially inconsistent with the GCA. The answer here turns on
subsection (B) of § 921(a)(3). That provision of the statute
permits the agency to regulate the “frame or receiver of any
such weapon.” As the Fifth Circuit saw it, this language
reaches only fnished frames or receivers. So those who
make, import, or sell partially complete frames or receivers
may do so free from the GCA's mandates, no matter how
quickly and easily their products can be fnished, and ATF is
powerless to hold otherwise. Once again, the plaintiffs ask
us to endorse that categorical conclusion. And, once again,
we fnd we cannot. The GCA reaches, and permits ATF to
regulate, at least some “partially complete” frames or receiv-
ers. § 478.12(c).
4
Separately, the dissent seems to dismiss the possibility that Congress
might use an artifact noun in a way that encompasses incomplete objects.
Post, at 502–503 (opinion of Thomas, J.). But the dissent does not dispute
that our task here, as ever, is to interpret the words Congress enacted
“consistent with their ordinary meaning.” Wisconsin Central Ltd. v.
United States, 585 U. S. 274, 278 (2018). Nor does the dissent dispute
that ordinary speakers sometimes use artifact nouns to reach incomplete
objects. In fact, the dissent ultimately concedes that even Congress
“might sometimes” do the same. Post, at 503–504, n. 7 (opinion of
Thomas, J.). At bottom, then, the dissent's only point appears to be that
“traditional methods of statutory interpretation” should guide us in as-
sessing whether Congress meant for a particular artifact noun to reach
incomplete objects. Ibid. On that, we agree. And here, as we have
seen, one of the most traditional tools for discerning statutory meaning—
contextual clues found in the pertinent statute itself—suggest that Con-
gress used the term “weapon” to reach at least some unfnished instruments
of combat. In saying as much, we do not suggest that Congress always
uses artifact nouns to reach incomplete objects—only that we are per-
suaded it did so here.
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A
W
orking with another example drawn from the record
helps illustrate why this is so. The frst photograph below
depicts the complete frame of a Glock-variant frearm, the
second a partially complete frame that Polymer80 sells.
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App. 259, 263.
The main differences between the completed frame and
Polymer80's product are the plastic tabs circled in red.
Brief for Petitioners 34–35. The record suggests that those
tabs “are easily removable by a person with novice skill,

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using common tools . . . , within minutes.” App. 262. Once
the
tabs are gone and a “few holes are drilled for the pins
that hold [other] parts in place—again, a task that anyone
can complete in minutes—the Polymer80 product is a fully
functional frame.” Brief for Petitioners 35.
A number of reasons persuade us that this qualifes as a
“frame” for purposes of subsection (B). First, like the word
“weapon” in subsection (A), the terms “frame” and “re-
ceiver” in subsection (B) are artifact nouns. And, as artifact
nouns, they may sometimes describe not-yet-complete ob-
jects. Recall the author who refers to her manuscript as a
novel, or your friend who calls his IKEA kit a table. In
much the same way, an ordinary speaker might well call
Polymer80's product a frearm “frame,” even though a little
work is required to complete it. Just look again at the sec-
ond photo. What else would you call it?
Next, consider how the GCA uses the words “frame” and
“receiver” elsewhere. Section 923(i) spells out the Act's se-
rialization mandate. It requires those who make or sell
“frearms” to identify their products “by means of a serial
number engraved or cast on the receiver or frame.” Though
this directive may seem simple enough, it is complicated
by the fact that the statutory defnition of “frearm” in-
cludes some incomplete “weapon[s],” “muffer[s],” “silenc-
er[s],” and “destructive device[s].” § 921(a)(3). Sometimes,
those items lack a fnished or prototypical frearm frame or
receiver. Yet, all the same, § 923(i) treats them as “fre-
arms” that must have a serial number engraved or cast on
their “frame[s]” or “receiver[s].” And if the words “frame”
and “receiver” encompass some unfnished and unconven-
tional frames or receivers in § 923(i), it is hard to see how
those same words might bear a more restrictive meaning
when they appear just a few sections away in § 921(a)(3)(B).
See Azar v. Allina Health Services, 587 U. S. 566, 574 (2019)
(recounting the usual rule that a word carries the same
meaning throughout a single statute); post, at 505 (Thomas,
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J., dissenting) (admitting that a contrary interpretation re-
quires
giving the terms “frame” and “receiver” different
meanings in different places).
Here, too, examples help. Imagine a handgun that is oth-
erwise ready to shoot, but contains Polymer80's incomplete
frame. An ordinary person, using ordinary tools, can fnish
the frame in minutes. App. 262. For reasons explored in
Part II, supra, that gun is a weapon capable of ready conver-
sion into a working frearm under subsection (A). So
§ 923(i) requires the gun's “frame”—the very item that isn't
fully fnished—to bear a serial number. Along similar lines,
consider silencers. They lack traditional frames, but § 923(i)
requires manufacturers and importers to serialize them. To
accommodate that instruction, ATF has long deemed the
“outer tube . . . that provides housing or a structure for the
primary internal component” to be a silencer's “frame or re-
ceiver.” 27 CFR § 478.12(b); accord, § 478.92(a)(4)(ii) (sup-
plying directions for “destructive devices”). In all these
ways and more, § 923(i) uses the phrase “frame or receiver”
to reach some unfnished and unconventional frames and re-
ceivers, making it only sensible to think the same phrase
does the same work a few doors away in § 921(a)(3)(B).
The novelty of the plaintiffs' complete-items-only reading
of subsection (B) supplies another strike against it. Without
question, ATF's new rule seeks to regulate a greater variety
of unfnished frames and receivers than the agency has in the
past. But it is equally true that, for decades, the agency has
consistently interpreted subsection (B) to reach some unfn-
ished frames and receivers, including ones no more fnished
than Polymer80's product. See, e. g., ATF, Are “80%” or
“Unfnished” Receivers Illegal? (Apr. 6, 2020), https://www.
atf.gov/frearms/qa /are-“80”-or-“unfnished”-receivers-illegal;
App. 117–118 (2013 guidance); id., at 5, 8, 10 (1990–1994 clas-
sifcation letters); id., at 22 (deeming a frame with additional
“material left on top” to be a “frearm”). And while “courts
must exercise independent judgment in determining the
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meaning of statutory provisions,” the contemporary and con-
sistent
views of a coordinate branch of government can pro-
vide evidence of the law's meaning. Loper Bright Enter-
prises v. Raimondo, 603 U. S. 369, 394 (2024).
5
Last but not least, the plaintiffs represent that they have
no “quarrel” with ATF's “prior practice.” Tr. of Oral Arg.
59. It is a concession that all but gives the game away. Of
course, the plaintiffs think the agency's new rule reaches fur-
ther than the statute can bear by seeking to regulate some
products too far removed from fnished frames or receivers.
But, for our purposes, what matters is that even the plain-
tiffs do not really insist that subsection (B) reaches only fn-
ished frames and receivers.
Here, again, our reasoning has its limits. In saying that
a product like Polymer80's qualifes as a “frame,” we do not
suggest that the GCA reaches, and ATF may regulate, any
combination of parts susceptible of conversion into a frame
or receiver with suffcient time, tools, and expertise. Like
the term “weapon,” the artifact nouns “frame” and “re-
ceiver” have their bounds. Some products may be so far from
a fnished frame or receiver that they cannot fairly be de-
scribed using those terms. But this case requires us to ex-
plore none of that. The plaintiffs do not challenge ATF's new
rule as applied to particular products. They argue only that
§ 478.12 is facially inconsistent with the GCA. And, here
again, we have no trouble rejecting that unqualifed view.
B
Resisting our conclusion on this score, the plaintiffs and
dissent press three main replies.
5
The dissent admits that ATF's prior practice was to “evaluat[e] the
level of completion” when deciding whether an unfnished object was a
“regulable frame or receiver.” Post, at 492 (opinion of Thomas, J.) (quoting
App. 23). So even if the new rule looks at different evidence in making
that same determination, post, at 499–500, it refects the agency's consist-
ent understanding that subsection (B) reaches some incomplete “frames
or receivers.”

482 BONDI
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First, they point to a linguistic difference between subsec-
ti
ons (A) and (B). In subsection (A), Congress chose to reg-
ulate “weapons” that “can readily be converted” into operat-
ing frearms. Meanwhile, in subsection (B) Congress spoke
only of “frames or receivers,” not parts that “can readily be
converted” into those things. And, as the plaintiffs see it,
that omission counsels against reading subsection (B) to
reach any unfnished frames or receivers. Brief for Re-
spondent VanDerStok et al. 19; see also post, at 498–499
(Thomas, J., dissenting) (making a similar point).
This argument fails to persuade us for a number of familiar
reasons. For one, it does not account for the fact that ordi-
nary speakers sometimes use unadorned artifact nouns like
“weapon,” “frame,” or “receiver” to reach unfnished articles.
Adopting the plaintiffs' argument would also require us to
read the phrase “frame or receiver” in § 921(a)(3)(B) to
embrace only fnished products, even though § 923(i)'s use
of the same phrase sweeps more broadly. To accept this
argument, we would have to disregard as well the plain-
tiffs' concession that the terms “frame” and “receiver” in
subsection (B) are properly understood, as they have been
long understood, to reach some unfi nished frames or
receivers.
Even beyond all that, reading subsection (B) in light of
subsection (A) does more to undermine than to advance the
plaintiffs' cause. Subsection (B) speaks of the “frame or re-
ceiver o f any such w eapo n. ” § 921(a)(3)(B) (emphasis
added). That italicized phrase refers us back to weapons
encompassed by subsection (A). And, as we have seen, the
term “weapon” in subsection (A) encompasses some things
that are not yet ft for effective use in combat, including
starter guns and disassembled rifes, as well as certain
weapon parts kits. Subsection (B) expressly incorporates
that defnition of “weapon.” And, if anything, the fact that
Congress used one artifact noun (“weapon”) in subsection (B)
to reach some unfnished articles suggests it used two other
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artifact nouns (“frame” and “receiver”) in the same way in
the
same provision.
Second, the plaintiffs and the dissent contend, our inter-
pretation of subsection (B) could invite a serious unintended
consequence under a separate statute, the National Fire-
arms Act (NFA), ch. 757, 48 Stat. 1236. That law bans the
possession of “machinegun[s],” a term Congress
has defned to include the “frame or receiver” of “any
such weapon.” 26 U. S. C. § 5845(b). Interpreting the GCA
to reach some unfnished frames or receivers, the plaintiffs
reason, might lead the government to attempt a similar read-
ing of the NFA. And if the government takes that step,
the plaintiffs suggest, it might next attempt to classify
the receiver of an AR–15 rife as a “machinegun” because
it “is possible to convert” those receivers “to function as
machinegun receivers.” Brief for Respondent VanDerStok
et al. 15; see also post, at 500 (Thomas, J., dissenting). That
result, the plaintiffs warn, could leave many Americans
facing new and unforeseen criminal liability for possession
of a “machinegun” simply because they own a “popular”
and “commonly avai lable” r i fle. Br ief for Respon-
dent VanDerStok et al. 22 (quoting Garland v. Cargill, 602
U. S. 406, 430 (2024) (Sotomayor, J., dissenting)); 87 Fed.
Reg. 24652.
The plaintiffs' fears are misplaced. The government rep-
resents that AR–15 receivers do not “qualify as the re-
ceiver of a machinegun.” Reply Brief 11–12. Nor, the gov-
ernment emphasizes, has ATF ever “suggested otherwise.”
Ibid. Much the same can be said of our reasoning today.
As we have stressed, a statute's text and context are criti-
cal to determining whether (and to what extent) Con-
gress used an artifact noun to reach unfnished objects.
And, without doubt, the NFA and the GCA are different
statutes passed at different times to address different prob-
lems using different language. Our analysis of the GCA
thus does not begin to suggest that ATF possesses authority
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to reg u late AR–15 receivers as mach i neg uns under
the
NFA.
Third, the plaintiffs criticize ATF's rule for permitting the
agency to consider “jigs,” “tools,” and “instructions” when
deciding whether an incomplete “frame or receiver” is close
enough to the fnished product to fall under subsection (B).
Brief for Respondent VanDerStok et al. 25–26. The dissent
echoes the complaint, offering a photo from the record de-
picting various tools and jigs. See post, at 501 (opinion of
Thomas, J.). But if this is a problem at all, it is one for
another day. As litigated, this case does not call on us to
address what weight, if any, ATF may lawfully give jigs,
tools, and instructions when deciding whether a frame or re-
ceiver is present. This case requires us to answer only
whether subsection (B) reaches some incomplete frames or
receivers. Saying that it does is enough to resolve the dis-
pute before us.
*
The plaintiffs close by asking us to invoke the rule of lenity
or the doctrine of constitutional avoidance to resolve in their
favor any ambiguities about § 921(a)(3). Brief for Respond-
ent VanDerStok et al. 38; see also post, at 511–512 (Thomas,
J., dissenting). But neither lenity nor avoidance has any role
to play where “text, context, and structure” decide the case.
Van Buren v. United States, 593 U. S. 374, 393–394 (2021).
And even if ambiguities at the outer boundaries of subsec-
tions (A) and (B) emerge in future disputes involving the
application of those provisions to particular products, no
room for doubt exists about the answer to the question the
parties have posed to us. The GCA embraces, and thus per-
mits ATF to regulate, some weapon parts kits and unfnished
frames or receivers, including those we have discussed. Be-
cause the court of appeals held otherwise, its judgment is
reversed, and the case is remanded for further proceedings
consistent with this opinion.
It is so ordered.
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485
Sotomayor, J., concurring
Justice Sotomayor, concurring.
I
join the Court's opinion in full. I write separately to
address two points raised in the writings that follow. The
frst is a concern that ATF's rule might leave regulated enti-
ties in doubt about when and how to comply with the Gun
Control Act. See post, at 486 (Kavanaugh, J., concurring).
That worry is unfounded.
For more than half a century, frearms dealers, manufac-
turers, and importers have complied with the Gun Control
Act's requirements. They have marked their products with
serial numbers, kept records of frearm sales, and conducted
background checks for prospective buyers. See 18 U. S. C.
§§ 922(t), 923(g)(1)(A), 923(i). These requirements are not
new to the industry, and covered entities know they must
maintain familiarity with the statute and accompanying reg-
ulations to run their businesses. In fact, the Act requires
such entities to obtain federal licenses before selling, manu-
factur ing, or impor ting any firear ms in the first place.
§ 923(a).
What is new is that some manufacturers have sought to
circumvent the Act's requirements by selling easy-to-
assemble frearm kits and frames, which they claim fall outside
the statute's scope. See 87 Fed. Reg. 24652, 24655, 24686
(2022). ATF's rule simply confrms what was already clear:
The Gun Control Act does not tolerate such evasion. Its plain
text covers frearm kits and unfnished frames or receivers
designed for ready conversion, as the Court explains. So,
for entities who seek to comply with the Act in good faith,
ATF's rule should come as no surprise. Nor should it create
any diffculty discerning how to abide by the law.
To the extent any manufacturer has doubts about whether
a particular product qualifes as a covered frearm, moreover,
it can eliminate uncertainty by seeking clarifcation from the
agency. ATF encourages manufacturers to submit poten-
tially covered products to the agency for classifcation deci-
sions. See Brief for Petitioners 5 (citing Dept. of Jus-
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Kavanaugh, J., concurring
tice, ATF, Offce of Enforcement Programs & Servs., ATF
Nati
onal Firearms Act Handbook 41 (ATF E-Publication
5320.8 rev. Apr. 2009)); 27 CFR § 478.92(c) (2023). Manufac-
turers have long taken advantage of that process, see, e. g.,
App. 8, 10–12, 21–22, 50–52, 53–54, and a failure to do so
might suggest willfulness on their part.
The second point I address is the suggestion that the Act
permits ATF to regulate only “all-but-assembled” weapon
parts kits and frames “as close to completion as possible.”
Post, at 513 (Alito, J., dissenting). The Court's opinion
speaks for itself on that point and others. I encourage read-
ers to go to the source, rather than rely on dissents, to under-
stand what the Court holds. See ante, at 467, 471–472, 478,
480–482, 484. It is the Court's ruling, not the one set forth
by the dissents, that binds the lower courts.
Justice Kavanaugh, concurring.
I join the Court's opinion in full. I add this concurrence
to briefy address mens rea issues with respect to ATF's
2022 rule.
Under ATF's rule, an individual or business acting in good
faith might nonetheless have substantial diffculty determin-
ing when weapon parts kits or unfnished frames or receivers
qualify as frearms—and thereby become subject to the Gun
Control Act's licensing, recordkeeping, serialization, and
background-check requirements. Some weapon parts kits
and unfnished frames or receivers may qualify as frearms,
and others may not. See ante, at 473, 481. The line is not
entirely clear. Despite the vagueness of the line, the penal-
ties for violations are signifcant and can include fnes and
imprisonment. See 18 U. S. C. § 924.
But importantly, under the Gun Control Act, someone can
be penalized for violating the licensing, recordkeeping, or se-
rialization requirements only if he does so “willfully.”
§ 924(a)(1)(D). To prove “willfulness, ” the Government
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487
Jackson, J., concurring
must demonstrate that an individual knew that his conduct
was
unlawful, not merely that he knew the facts that made
his conduct unlawful. Bryan v. United States, 524 U. S. 184,
191–196 (1998). Therefore, with respect to ATF's rule, the
“willfulness” requirement should help prevent the Govern-
ment from unfairly penalizing an individual who is not aware
that his conduct violates the law.
As to background-check violations, by contrast, the statute
penalizes violations committed “ know ingly. ” §§ 922(t),
924(a)(5). The “knowingly” mens rea requires “proof of
knowledge of the facts that constitute the offense.” Id., at
193. Unlike the “willfully” mens rea, it generally does not
require knowledge that the conduct was unlawful. See id.,
at 192–193. That lesser “knowingly” mens rea requirement
could therefore create concerns about fair notice, at least in
certain cases. See Wooden v. United States, 595 U. S. 360,
379 (2022) (Kavanaugh, J., concurring).
That said, at oral argument, the Government represented
that it would “likely” decline to “charge someone” for a
background-check violation in the “kind of situation” where
the individual was not aware that he was violating the law.
Tr. of Oral Arg. 46–47. As the Government seemed to rec-
ognize, if the Government were to charge a background-
check violation against an individual who was unaware that
he was violating the law, that defendant might have a due
process argument based on lack of fair notice. I expect that
the Government will seek to avoid that potential fair-notice
problem by adhering to its oral-argument representation
that it wou ld l ikely decl i ne to br i ng charges i n those
circumstances.
Justice Jackson, concurring.
To me, the nature of the claim at issue in this case makes
its resolution quite straightforward. No one disputes that
Congress delegated rulemaking authority to the Executive
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Branch through the Gun Control Act of 1968, as amended.
See
18 U. S. C. § 926(a). Nor is it contested that the Bureau
of Alcohol, Tobacco, Firearms and Explosives, an Executive
Branch agency, relied on that delegated authority to pro-
mu lgate the cha l lenged r u le. Before us, respondents
claim only that portions of the resulting rule exceed the
agency's statutory authority. See 5 U. S. C. § 706(2)(C).
Our judicial charge, then, is to evaluate the scope of the
Gun Control Act's delegation of authority to the agency,
and to determine whether the agency's actions trans-
gressed those bounds. That limited exercise should be
dispositive.
Proper excess-of-authority review must focus on actual
statutory boundaries, not on whether the agency's discre-
tionary choices overlap precisely with what we, as unelected
judges, would have done if we were standing in the agency's
shoes. And where, as here, the statute's boundaries do not
foreclose the agency's action, the excess-of-authority claim
should meet its end. I concur because I read the Court's
opinion to be consistent with this view.
Justice Thomas, dissenting.
The Government asked this Court just last Term to “ `re-
write' ” statutory text so that it could regulate semiauto-
matic weapons as machineguns. Garland v. Cargill, 602
U. S. 406, 428 (2024). We declined to do so. The Govern-
ment now asks us to rewrite statutory text so that it can
regulate weapon-parts kits. This time, the Court obliges.
I would not. The statutory terms “frame” and “receiver”
do not cover the unfnished frames and receivers contained
in weapon-parts kits, and weapon-parts kits themselves do
not meet the statutory defnition of “frearm.” That should
end the case. The majority instead blesses the Govern-
ment's overreach based on a series of errors regarding both
the standard of review and the interpretation of the statute.
I respectfully dissent.
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489
Thomas, J., dissenting
I
A
In
1934, Congress enacted the National Firearms Act
(NFA), the frst federal statute to regulate the frearms in-
dustry. Congress enacted this statute to “provide for the
taxation of manufacturers, importers, and dealers in certain
frearms and machine guns, to tax the sale or other disposal
of such weapons, and to restrict importation and regulate
interstate transportation thereof.” Ch. 757, 48 Stat. 1236.
The NFA defned “frearm” narrowly. The term covered
only certain short-barreled shotguns or rifes, machineguns,
and silencers or muffers. Ibid. Congress broadened that
defnition four years later through the Federal Firearms Act
of 1938 (FFA), defning “frearm” to include “any weapon . . .
designed to expel a projectile or projectiles by the action of
an explosive . . . or any part or parts of such weapon.” 52
Stat. 1250 (emphasis added). With minor amendments not
relevant here, that defnition endured for about 30 years.
In 1968, Congress replaced the FFA with the Gun Control
Act (GCA). The GCA, which remains in effect today, is the
principal federal law regulating the commercial frearm mar-
ket. See Pub. L. 90–618, 82 Stat. 1213. It requires manu-
facturers and dealers of frearms to have a federal license,
and, in most cases, to conduct background checks, maintain
records, and apply serial numbers to their frearms. See 18
U. S. C. §§ 922(t) and 923(a), (g)(1)(A), and (i). The GCA also
imposes criminal sanctions for a variety of well-known fre-
arms offenses. See, e. g., § 922(g) (prohibiting large swaths
of people from shipping, transporting, possessing, or receiv-
ing a “frearm”); § 924(c) (providing a sentencing enhance-
ment for persons who carry a “frearm” during crimes of
violence or drug-traffcking crimes).
The GCA sets forth a narrower defnition of “frearm” than
the FFA did. Its defnition, which governs all of “Chapter
44—Firearms,” §§ 921–934, states that a “frearm” is:
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“(A) any weapon (including a starter gun) which will or
is
designed to or may readily be converted to expel a
projectile by the action of an explosive; (B) the frame or
receiver of any such weapon; (C) any frearm muffer or
frearm silencer; or (D) any destructive device. Such
term does not include an antique frearm.” § 921(a)(3).
Whereas the FFA had treated “any part or parts” of a
frearm as a regulable frearm, the GCA deems only a fre-
arm's “frame or receiver” to be frearm parts that qualify as
a frearm in their own right. § 921(a)(3)(B).
Congress left the terms “frame” and “receiver” undefned.
See § 921. Shortly after the GCA's enactment, the Bureau
of Alcohol and Tobacco Tax Division
1
promulgated a regula-
tion defning “frame or receiver” as “[t]hat part of a frearm
which provides housing for the hammer, bolt or breechblock,
and fring mechanism, and which is usually threaded at its
forward portion to receive the barrel.” 33 Fed. Reg. 18558
(1968) (emphasis deleted).
2
That regulatory defnition made sense. At the time of the
GCA's enactment, the term “frame” was generally under-
stood to mean “the basic structure and principal component
of a frearm.” C. Mueller & J. Olson, Small Arms Lexicon
and Concise Encyclopedia 87 (1968) (Olson's). And, the term
“receiver” was generally understood to mean the “part of a
gun that houses the breech action and fring mechanism.”
Id., at 168. Thus, ATF's initial defnition of “frame or re-
ceiver” accorded with the terms' ordinary meanings. See
33 Fed. Reg. 18558 (“[t]hat part of a frearm which provides
1
The Bureau of Alcohol and Tobacco Tax Division was the predecessor
entity to the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).
For the remainder of this opinion, I refer to the relevant agency at any
time as “ATF.”
2
The GCA authorizes the Attorney General to “prescribe only such
rules and regulations as are necessary to carry out” the statute. 18
U. S. C. § 926(a). The Attorney General has delegated this authority to
ATF. See 28 CFR § 0.130(a) (2023).
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Thomas, J., dissenting
housing for the hammer, bolt or breechblock, and fring
mechanism”).
A
TF's defnition also aligned with the GCA, because for
“any weapon” to “expel a projectile by the action of an explo-
sive,” § 921(a)(3)(A), the weapon must have both a mecha-
nism that will initiate that explosion and a way to seal the
fring chamber. In other words, the weapon must have a
“frame” or “receiver.” See Olson's 87, 168. Thus, by defn-
ing frame or receiver as the parts of a gun that provide
“housing for the hammer, bolt or breechblock, and fring
mechanism,” 33 Fed. Reg. 18558, ATF's initial defnition ft
neatly into the statutory scheme. This understanding of
“frame” and “receiver” governed for over 50 years.
But, ATF recently changed course, in an effort to regulate
so-called ghost guns—i.e., privately made frearms built from
kits or collections of unfnished parts. To tackle what it per-
ceived to be the “homeland security threat” posed by the
“wide availability of ghost guns,” the agency promulgated a
rule redefning “frearm,” “frame,” and “receiver.” Defni-
tion of “Frame or Receiver” and Identifcation of Firearms,
87 Fed. Reg. 24652, 24658 (2022) (Rule) (internal quotation
marks omitted). Without any change to the statute, this
Rule expanded the regulatory defnition of “frearm” to in-
clude “a weapon parts kit that is designed to or may readily
be completed, assembled, restored, or otherwise converted
to expel a projectile by the action of an explosive.” 27 CFR
§ 478.11 (2023). It also broadened the defnition of “frame
or receiver” to include “a partially complete, disassembled,
or nonfunctional frame or receiver, including a frame or
receiver parts kit, that is designed to or may readily be com-
pleted, assembled, restored, or otherwise converted to func-
tion as a frame or receiver.” § 478.12(c).
One of the Rule's critical innovations is the manner in
which it allows ATF to determine whether an object is
“clearly identifable”—and thus regulable—as an unfnished
frame or receiver:
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“When issuing a classifcation, the Director may consider
any
associated templates, jigs, molds, equipment, tools,
instructions, guides, or marketing materials that are
sold, distributed, or possessed with the item or kit, or
otherwise made available by the seller or distributor of
the item or kit to the purchaser or recipient of the item
or kit.” Ibid.
“Prior to this rule, ATF did not examine templates, jigs, or
other items and materials in determining whether partially
complete frames or receivers were `firearms' under the
GCA.” 87 Fed. Reg. 24668; see also Tr. of Oral Arg. 39–
40 (acknowledging the change). Instead, ATF looked to the
object itself to determine whether it was sufficiently com-
plete to constitute a regulable frame or receiver. See, e. g.,
App. 23 (2004 guidance letter from ATF explaining that the
agency “evaluates the level of completion of the submitted
sample . . . and makes a comparison with a sample of a com-
pleted firearm of the same type”). The new definition, how-
ever, expanded the meaning of “frame” and “receiver” to in-
corporate items entirely separate from the object itself.
According to ATF, whether an unusable, unfinished piece of
metal constitutes a regulable “frame or receiver” can turn
on a manufacturer's “marketing materials.” 87 Fed. Reg.
24668.
ATF offered one meager limit on its broad, new defnitions:
Under the Rule, “raw material,” such as an “unformed block
of metal” or “liquid polymer,” will not constitute a regulable
frame or receiver. 27 CFR § 478.12(c).
B
Before the Rule took effect, a group of individuals and
manufacturers of weapon-parts kits fled a petition for re-
view challenging the Rule's new defnitions of “frame or re-
ceiver” and “frearm.” As relevant here, the plaintiffs al-
leged that the Rule exceeded ATF's “statutory jurisdiction,
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Thomas, J., dissenting
authority, or limitations” under the Administrative Proce-
dure
Act (APA), 5 U. S. C. § 706(2)(C). See Amended Peti-
tion for Judicial Review of Agency Action and Request for
Declaratory Judgment and Injunctive Relief in No. 4:22–cv–
691 (ND Tex., Oct. 5, 2022), ECF Doc. 93, p. 42 (alleging
Rule's expansive defnitions provided ATF “new, additional
authority in excess of that proposed, considered, debated, or
passed by Congress”).
The District Court granted summary judgment to the
plaintiffs and vacated the Rule. VanDerStok v. Garland,
680 F. Supp. 3d 741 (ND Tex. 2023). The Fifth Circuit af-
frmed in relevant part. VanDerStok v. Garland, 86 F. 4th
179 (2023). It held that ATF's redefnition of “frame or re-
ceiver” was an “impermissible extension of the statutory
text,” id., at 189, and that the agency's attempt to redefne
“frearm” to include a weapon-parts kit “stretche[d] the [stat-
ute's] words too far,” id., at 192. The Government's effort
“to justify its unprecedented expansion of the GCA,” the
court explained, “collapses upon a cursory reading of the
text.” Id., at 193.
Judge Oldham wrote separately to highlight the “stagger-
ing ” implications of ATF's new position, particularly with
respect to the AR–15, “the most popular rife in America.”
Id., at 208 (concurring opinion). Observing that the Rule
regulates frames and receivers according to what they might
become rather than what they are, and that an AR–15's semi-
automatic receiver can “ `readily be converted' ” into a fully
automatic receiver with relative ease, he concluded that, on
ATF's logic, the Government may regulate AR–15s as ma-
chineguns. Id., at 207–208. If ATF were correct, Judge
Oldham cautioned, “then millions and millions of Americans
would be felons-in-waiting.” Id., at 208.
This Court granted certiorari to decide two questions:
whether the Rule's new defnition for frames and receivers
fts within the statutory defnition of “frame or receiver”
under the GCA, see § 921(a)(3)(B); and whether the statutory
term “frearm” can cover weapon-parts kits.
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II
Before
turning to the questions presented, a threshold
issue is the applicable legal standard for analyzing the plain-
tiffs' APA challenge. Applying traditional principles of
statutory interpretation, the Fifth Circuit asked whether the
Rule “conficts with the plain language of the GCA” or
“cast[s] a wider net than Congress intended.” 86 F. 4th, at
190, 194. We took this case to determine whether the Fifth
Circuit was correct to answer “yes.” I would undertake the
same inquiry as the Fifth Circuit and ask only whether the
Rule contravenes “clear statutory text” or otherwise “ex-
ceeds the [GCA's] legislatively-imposed limits on agency au-
thority.” Id., at 182.
The majority takes a different approach. Asserting that
the plaintiffs conceded to having brought a “ `facial' ” chal-
lenge, the Court “take[s]” this characterization “as given,”
and analyzes the challenge as a facial attack.
3
Ante, at 467.
In particular, the Court assumes, arguendo, that the regula-
tory defnitions are valid so long as they cover “at least some
weapon parts kits.” Ante, at 473. This approach superf-
cially appears to apply a framework similar to that of United
States v. Salerno, 481 U. S. 739 (1987). There, the Court
explained that, to prevail in a “facial challenge” to a statute,
the challenger must establish that “no set of circumstances
exists under which the Act would be valid.” Id., at 745.
This approach seems plainly inapt in a challenge to a regu-
latory defnition. “To `defne' is . . . `to settle' or `to establish
or prescribe authoritatively.' ” Puerto Rico v. Franklin Cal.
3
While the Government characterized the plaintiffs' lawsuit as a facial
challenge in passing, see ante, at 467, the parties did not seriously litigate
the relevant standard, see post, at 514–515 (Alito, J., dissenting). And,
at oral argument, plaintiffs' counsel appeared to endorse a standard simi-
lar to the one that the Fifth Circuit applied. See Tr. of Oral Arg. 80
(arguing that ATF would have “gone beyond their authority” by defning
“frame or receiver” to “include items that may readily be converted to
frames or receivers”).
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Thomas, J., dissenting
Tax-Free Trust, 579 U. S. 115, 126 (2016) (quoting Black's
Law
Dictionary 380 (5th ed. 1979)); see also id., at 534 (12th
ed. 2024) (equating “defne” with “To state or explain explic-
itly”; “[t]o fx or establish (boundaries or limits)”; and “[t]o
set forth the meaning of (a word or phrase)”). The point of
defning a term in a regulation is therefore to show what
the law permits and what it prohibits. But, a regulatory
defnition that is accurate in only a single valid application
cannot possibly “explain explicitly,” “fx or establish,” or “set
forth the meaning ” of a statutory term. Id., at 534.
Consider a hypothetical statute that defnes “motorcycle”
as “a motor-powered, two-wheeled vehicle with pedals.” If
a regulatory defnition copied the same language, and then
added that “the term shall include any motorized vehicle,”
the regulatory defnition obviously would be wrong. Not
every motorized vehicle is a motorcycle, and the fact that
some motorized vehicles happen to be motor-powered, two-
wheeled vehicles with pedals does not suggest otherwise.
It is diffcult to see how an overbroad regulatory defnition
becomes defensible simply because some set of circumstances
exists in which the regulatory defnition overlaps with the
statutory defnition.
4
4
Dissenting in Babbitt v. Sweet Home Chapter, Communities for Great
Ore., 515 U. S. 687 (1995), Justice Scalia criticized the application of a simi-
lar standard as “unprecedented” in the context of challenges to regulatory
defnitions. Id., at 731. Using an example of a statute prohibiting “ `pre-
meditated killing of a human being,' ” Justice Scalia explained that a chal-
lenge to an implementing regulation that prohibits “ `killing a human
being ' ” “would not be rejected on the ground that, after all, it could be
applied to a killing that happened to be premeditated.” Id., at 731–732.
“It could not be applied to such a killing, because it does not require the
factfnder to fnd premeditation, as the statute requires.” Id., at 732. In
other words, the regulatory defnition would be unlawful in every applica-
tion because it allows the factfnder to determine liability without meeting
the statute's requirements. A regulatory defnition that incorporates
terms exceeding the statutory text creates a similar problem, as it permits
liability based on elements outside the statute's scope.
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Treating challenges to regulatory defnitions as “facial
cha
llenges” has substantial implications. If a regulatory
defnition survives APA challenge so long as just one item it
covers also happens to be covered by the statute it purports
to interpret, it is diffcult to understand how an agency would
ever promulgate an invalid defnition. So long as it imports
the defnition Congress laid out in the statute, the agency
can sweep in whatever additional conduct it wishes. No
matter how far the agency expands its regulatory defnition,
the statutory defnition inevitably will capture at least some
of it.
To its credit, the majority attempts to confne the effects of
its approach to the facts of this case. Because the majority
assumes the relevant legal standard without deciding it, it
refrains from mandating this framework. Rather, it rests
on its conclusion that the plaintiffs essentially conceded that
the facial-challenge standard applies, and it takes the appli-
cation of that standard “as given” for this case only. Ante,
at 467; see ante, at 468, n. 2 (“[W]e believe the better course
is to leave further analysis of the proper test for another day
and address the parties' dispute as they have chosen to frame
it”). So long as lower courts do not equate an APA chal-
lenge with a “facial” one, they are free to disregard the ma-
jority's analysis and hold that the Rule exceeds ATF's statu-
tory authority.
5
5
Although the majority avoids settling whether the framework in
United States v. Salerno, 481 U. S. 739 (1987), is appropriate for regulatory
challenges in the APA context, the Court may one day have to decide
this important question. This Court has at least occasionally applied the
Salerno framework in regulatory challenges. See, e. g., Reno v. Flores,
507 U. S. 292, 301 (1993); INS v. National Center for Immigrants' Rights,
Inc., 502 U. S. 183, 188 (1991). But, as Justice Alito observes, “neither
decision explained why the Salerno rule should be extended in that way.”
Post, at 515 (dissenting opinion). If a regulation is so overbroad that it
has only a single valid application, it would seem plainly “arbitrary” or
“capricious” under the APA, 5 U. S. C. § 706(2)(A), making a Salerno-like
inquiry inapposite. Perhaps the majority's analysis would differ if it were

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Thomas, J., dissenting
III
As
for the questions presented, start with the question
whether the Rule's new defnition for frames and receivers
can stand. Ordinary principles of statutory interpretation
make plain that the Rule sweeps too far: The terms “frame”
and “receiver” in § 921(a)(3)(B) do not cover “partially com-
plete, disassembled, or nonfunctional frame[s] or receiver[s].”
27 CFR § 478.12(c). The majority reaches a different conclu-
sion based on several interpretive errors. Most notably, the
majority proceeds under the faulty premise that our stand-
ard rules of statutory interpretation do not apply to “a word
for a thing created by humans.” Ante, at 470.
A
“In statutory interpretation disputes, a court's proper
starting point lies in a careful examination of the ordinary
meaning and structure of the law itself.” Food Marketing
Institute v. Argus Leader Media, 588 U. S. 427, 436 (2019).
As relevant here, § 921(a)(3) defnes “frearm” to include “(A)
any weapon (including a starter gun) which will or is de-
signed to or may readily be converted to expel a projectile
by the action of an explosive,” and “(B) the frame or receiver
of any such weapon.” Because the GCA defnes neither
“frame” nor “receiver,” “ `we give [each] term its ordinary
meaning.' ” Encino Motorcars, LLC v. Navarro, 584 U. S.
79, 85 (2018).
The parties agree that, in 1968, the terms “frame” and “re-
ceiver” were understood to refer to “ `the basic structure and
principal component of a frearm,' ” and “the `part of a gun
that houses the breech action and fring mechanism.' ” Brief
asking whether the Rule was arbitrary and capricious rather than whether
it was “ `in excess of statutory . . . authority.' ” Ante, at 466. But, be-
cause the majority's approach is untenable for the reasons explained in
this opinion, I leave the broader question of Salerno's applicability in the
APA context for another day.
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for Petitioners 32 (quoting Olson's 87, 168); Brief for Re-
spondent
VanDerStok et al. 7 (same). But, ATF's Rule con-
ficts with this accepted meaning in at least two ways.
First, it defnes “frame or receiver” to include objects that
are not frames or receivers, but that may be “converted” into
them in the future. 27 CFR § 478.12(c). Second, it permits
ATF to deem an object a frame or receiver based on “mar-
keting materials” and other materials merely associated with
it. Ibid.
1
The ordinary meaning of “frame or receiver” does not in-
clude objects that may be “converted” into a frame or re-
ceiver. Ibid. As the Government itself admits, the word
“ `convert' ” means “ `[t]o change into another form, sub-
stance, state, or product; transform; transmute.' ” Brief for
Petitioners 19–20 (quoting American Heritage Dictionary
291 (1969)). If an object can become a frame or receiver
only after it is “change[d] into another form, substance, state,
or product,” it is diffcult to understand how the object can
be considered a frame or receiver even before the change
occurs. Ibid. As the Fifth Circuit put it, “a part cannot be
both not yet a receiver and a receiver at the same time.” 86
F. 4th, at 190 (internal quotation marks omitted).
The structure of § 921(a)(3) confrms that objects that are
not yet frames or receivers do not meet the statutory defni-
tion of “frame or receiver.” § 921(a)(3)(B). Subsection (A)
of § 921(a)(3) covers weapons that are not yet functional guns
but that “may readily be converted” into them. And, the
statute makes clear that subsections (C) (muffers and silenc-
ers) and (D) (destructive devices), also cover more than fn-
ished, operable products. See § 921(a)(25) (defning “muf-
fer” and “silencer” to include “any combination of parts . . .
for use in assembling ” such objects); § 921(a)(4)(C) (defning
“destructive device” to include any “combination of parts”
for “converting any device into any destructive device” de-
scribed in the statute and “from which a destructive device
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499
Thomas, J., dissenting
may be readily assembled”). In contrast, subsection (B)
covers
only a weapon's “frame or receiver.”
“[W]hen Congress includes particular language in one sec-
tion of a statute but omits it in another section of the same
Act, it is generally presumed that Congress acts intention-
ally and purposely in the disparate inclusion or exclusion.”
Barnhart v. Sigmon Coal Co., 534 U. S. 438, 452 (2002) (inter-
nal quotation marks omitted). This principle holds particu-
lar force here, where Congress applied broadening language
to the subject matter of every subsection in § 921(a)(3) except
for subsection (B). Yet, in defning “frame” and “receiver”
to include objects that “may readily be completed, assem-
bled, restored, or otherwise converted to function as a frame
or receiver,” 27 CFR § 478.12(c), the Rule transplants the
“readily be converted” and “assembled” concepts from sub-
sections (A), (C), and (D) into subsection (B)—the very provi-
sion from which Congress omitted them.
The straightforward reading of § 921(a)(3) is the correct
one: Subsection (B)'s omission of the readily converted and
readily assembled concepts means that a “frame or receiver”
does not include objects that are not yet frames or receivers.
And, until promulgating the Rule, ATF agreed with this
understanding:
“Importantly, the `designed to' and `readily be con-
verted' language are only present in the frst clause
of the statutory defnition. Therefore, an unfnished
frame or receiver does not meet the statutory defnition
of `frearm' simply because it is `designed to' or `can
readily be converted into' a frame or receiver. Instead,
a device is a frearm either: (1) because it is a frame or
receiver or; (2) it is a device that is designed to or can
readily be converted into a device that `expel[s] a projec-
tile by the action of an explosive.' ” Memorandum of
Law in Syracuse v. ATF, No. 1:20–cv–06885 (SDNY, Jan.
29, 2021), ECF Doc. 98, p. 14 (Brief for ATF) (citation
omitted).
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See also id., at 36–39 (explaining why “An Unmachined
F
rame or Receiver Cannot Be Readily Converted Into a De-
vice that Expels a Projectile”). ATF was right the frst
time.
Tellingly, ATF's new interpretation seems to invite “stag-
gering ” consequences. 86 F. 4th, at 208 (Oldham, J., concur-
ring). The NFA defnes “ `machinegun' ” as “any weapon
which shoots . . . automatically more than one shot, without
manual reloading, by a single function of the trigger,” and
“include[s]” in that defnition “the frame or receiver of any
such weapon.” 26 U. S. C. § 5845(b). ATF has defned
“frame or receiver” in the NFA to “have the same meaning
as in § 478.12”—the provision that defnes those terms under
the GCA. 27 CFR § 479.11. And, although an unmodifed
AR–15 is a semiautomatic weapon, “every single AR–15 can
be converted to a machinegun using cheap, fimsy pieces of
metal—including coat hangers.” 86 F. 4th, at 208 (Old-
ham, J., concurring).
If an object already is what it may be converted into, 27
CFR § 478.12(c), then semiautomatic AR–15s would seem to
be partially complete, automatic machineguns. This reason-
ing exposes the manufacturers, sellers, and owners of AR–
15s to criminal liability under the NFA. See 26 U. S. C.
§§ 5861, 5871. But, Congress does not “hide elephants in
mouseholes.” Whitman v. American Trucking Assns., Inc.,
531 U. S. 457, 468 (2001). An interpretive approach that
would allow ATF to regulate the most popular semiauto-
matic rife in America under a statute addressing automatic
machineguns should give us pause. Cf. Dubin v. United
States, 599 U. S. 110, 130 (2023) (“Time and again, this Court
has prudently avoided reading incongruous breadth into
opaque language in criminal statutes”).
2
The Rule's defnitions of “frame” and “receiver” also con-
travene ordinary meaning by allowing ATF to classify ob-
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501
Thomas, J., dissenting
jects as frames or receivers based on criteria other than
the
object's physical characteristics. Under the Rule, any
“tools, instructions, guides, or marketing materials” that are
“made available by the seller” can convert an unregulated
piece of metal into a regulated “frame or receiver.” 27 CFR
§ 478.12(c). Put another way, the mere presence of things
distinct from the object at issue can somehow transform the
character of the object itself.
Page Proof Pending Publication
Figure 1. See Dept. of Justice, ATF, Open Letter to All Federal Firearms
Licensees 3, 6 (Sept. 27, 2022), https://www.atf.gov/frearms/docs/open-
letter/a l l-ffls-september-2022-i mpac t-fi na l-r u le-2021-05f-par tia l ly-
complete-ar/download.
Figure 1, supra, illustrates the Rule in action. Both im-
ages in Figure 1 depict unfnished receivers. Both lack ma-
chining and indexing in the key areas. The only difference

502 BONDI
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is the presence of a jig and drill bits. Yet, according to the
Ru
le, these extraneous items make an unfnished receiver a
regulable frearm.
The presence of items such as jigs or “marketing materi-
als”—that are not, and never could be, part of a frame or
receiver—has no bearing on whether a piece of metal or plas-
tic constitutes “the basic structure and principal component
of a frearm.” Olson's 87. Because those extrinsic items
have no impact on the ordinary meanings of “frame” or “re-
ceiver,” the regulatory defnition exceeds statutory text by
using such items to expand the scope of those statutory
terms. Cf. Encino Motorcars, 584 U. S., at 85 (an undefned
statutory term receives its ordinary meaning).
B
The majority leaves the issue of extrinsic objects for an-
other day, deeming the issue irrelevant under its question-
able facial-challenge standard. Ante, at 484. The majority
thus defends only the Rule's coverage of items that may
become frames or receivers. To do so, it substitutes novel
linguistic labels for traditional statutory interpretation; mis-
takes outlier defnitions for exemplars; and improperly im-
ports attributes of one provision into another.
1
The majority's statutory analysis deviates dramatically
from the “careful examination of the ordinary meaning and
structure of the law itself ” that is typically at the core of
this Court's interpretive approach. Food Marketing Insti-
tute, 588 U. S., at 436. Drawing heavily from an amicus
brief and an academic paper,
6
the majority asserts that “the
6
See Brief for Professors and Scholars of Linguistics and Law as Amici
Curiae; S. Grimm & B. Levin, Artifact Nouns: Reference and Countability,
in 2 Proceedings of the Forty-Seventh Annual Meeting of the North East
Linguistic Society 55 (2017) (Grimm).
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terms `frame' and `receiver' in subsection (B) are artifact
nouns,
” ante, at 479—that is, they are words for “thing[s]
created by humans,” ante, at 470. The majority argues that
this type of noun is fexible enough to encompass unfnished
objects. It explains that, in casual conversation, one might
refer to an artifact noun such as an “unfnished manuscript”
as a “novel,” or an unassembled piece of furniture from
IKEA as a “table.” Ante, at 470–471. Thus, the majority
argues, a “frame” or “receiver” “may sometimes describe
not-yet-complete” frames or receivers. Ante, at 479.
It is beside the point whether, in casual conversation, some
people might use “a word for a thing created by humans” to
discuss unfnished versions of that “thing.” Ante, at 470.
“In statutory drafting, where precision is both important and
expected, the sort of colloquial usage on which the [majority]
relies is not customary.” Allison Engine Co. v. United
States ex rel. Sanders, 553 U. S. 662, 670 (2008). We have
expressly “presumed” that Congress does not “draft its
laws” with the informality of “casual conversation.” Arca-
dia v. Ohio Power Co., 498 U. S. 73, 79 (1990).
Thus, we must evaluate the Rule's redefnition of “frame”
and “receiver ” based on the GCA's “entire st atutory
scheme,” Winkelman v. Parma City School Dist., 550 U. S.
516, 523 (2007), not the “ `stereotypical' conversational back-
ground” on which the majority relies, Grimm 58. That
scheme—as refected in the GCA's text, context, and struc-
ture—confrms that unfnished objects in a weapon-parts kit
do not meet § 921(a)(3)(B)'s terms. Supra, at 497–502.
Dressing up colloquial usage with the “artifact noun” label
cannot override this conclusion.
7
7
The majority suggests that I “dismiss the possibility that Congress
might use an artifact noun in a way that encompasses incomplete objects,”
and then defends its reliance on the artifact noun as just another way to
discern a statute's “ `ordinary meaning.' ” Ante, at 477, n. 4. I do not
doubt that Congress might sometimes intend to describe an incomplete
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2
The
majority further argues that, because Ҥ 923(i) uses
the phrase `frame or receiver' to reach some unfnished and
unconventional frames and receivers,” such as the “frame”
or “receiver” of a muffer or silencer, it is reasonable to inter-
pret § 921(a)(3)(B) to also cover unusual frames or receivers.
Ante, at 479–480. The majority's conclusion does not follow
its premise.
Section 921(a)(3)(C) defnes a frearm to include “any fre-
arm muffer or frearm silencer.” Section 923(i) requires
licensed importers and manufacturers to place a serial
number on a frearm's “receiver or frame.” To reconcile
§ 921(a)(3)(C) with § 923(i)'s requirement, muffers and silenc-
ers must have a “receiver or frame” even though they do not
as a matter of ordinary meaning. Thus, by regulation, ATF
deems a muffer's or silencer's “outer tube or modular piece”
to be its “frame or receiver.” 27 CFR § 478.12(b).
In the context of muffers and silencers, the terms “frame”
and “receiver” have context-specifc meanings that cannot be
generalized to other provisions in Chapter 44. As ATF ex-
plained, “[u]nder the GCA, licensed manufacturers and im-
porters must identify the frame or receiver of each frearm,
including a frearm muffer or silencer, with a serial number
object with “a word for a thing created by humans,” ante, at 470, or that
courts may legitimately give effect to that intent. But, my point is that
when courts determine whether a word refers to an incomplete or fnished
object, they apply traditional methods of statutory interpretation to ascer-
tain what “Congress intended to cover and did cover” in the relevant stat-
utes, United States v. Citroen, 223 U. S. 407, 424 (1912), not what “[a]
friend” might have meant in casual conversation, ante, at 471. In other
contexts, such as trade law, courts applying those methods have found that
Congress intended to treat incomplete versions of commercial products
differently from their completed counterparts. See, e. g., Citroen, 223
U. S., at 422–423 (applying different tariffs to pearls predrilled for use as
necklaces than to pearls that were already strung into a necklace). We
cannot invoke the concept of the “artifact noun” to displace this traditional
statutory analysis.
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in accordance with regulations.” 87 Fed. Reg. 24660. Call-
i
ng an “outer tube or modular piece” of a muffer or silencer
a “frame or receiver” thus may be justifed as an attempt to
square § 923(i) with Congress's decision to include muffers
and si lencers w ith i n the defi niti on of “firear m” under
§ 921(a)(3)(C). Cf. A. Scalia & B. Garner, Reading Law: The
Interpretation of Legal Texts 228 (2012) (Scalia & Garner)
(explaining that context may, in rare circumstances, justify
overriding a term's established meaning). But, the pre-
sumption of consistent usage is “particularly defeasible by
context,” see id., at 171, and there is no reason to think that
the agency's workaround for applying § 923(i) to muffers and
silencers should alter the ordinary meanings of “frame” and
“receiver” in other statutory provisions that do not implicate
the same problem. In this case, the statutory scheme makes
clear that § 921(a)(3)(B)'s “frame or receiver” language does
not include unfnished, inoperable objects even if one day
they may become frames or receivers. Supra, at 498–500.
3
The majority further asserts that “reading subsection (B)
in light of subsection (A)” actually “undermine[s]” the plain-
tiffs' position. Ante, at 482. Again, subsection (A) covers
any weapon which “may readily be converted” into a func-
tional gun. § 921(a)(3)(A). Subsection (B) specifes that a
frearm includes the “ `frame or receiver of any such
weapon.' ” Ante, at 482 (emphasis added by majority). Ac-
cording to the majority, that reference in subsection (B) im-
plicitly incorporates subsection (A)'s readily converted lan-
guage. And, because subsection (A) covers “starter guns
and disassembled rifes” that are “not yet ft for effective use
in combat,” ibid., the majority argues that subsection (B)
should also cover objects that are not yet usable. That con-
clusion does not follow.
The frames and receivers referred to in subsection (B) are
components of the “weapon[s]” referred to in subsection (A).
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While the majority is correct that subsection (A)'s readily
con
verted language covers weapons “not yet ft for effective
use in combat,” ibid., there is no reason to think that the
readily converted language in subsection (A) applies to the
component parts described in subsection (B)—and every rea-
son to think they do not. ATF recognized as much just a
few years ago, explaining that “the `designed to' and `readily
be converted' language are only present in the frst clause of
the statutory defnition. Therefore, an unfnished frame or
receiver does not meet the statutory defnition of `frearm'
simply because it is `designed to' or `can readily be converted
into' a frame or receiver.” Brief for ATF 14 (citation omit-
ted). The majority's examples of “starter guns and disas-
sembled rifes,” ante, at 482, underscore the point that an
inoperable weapon does not imply an inoperable frame or
receiver: While neither type of weapon is “ft for effective
use in combat,” ibid., their frames and receivers are typi-
cally operable.
“We do not lightly assume that Congress has omitted from
its adopted text requirements that it nonetheless intends to
apply, and our reluctance is even greater when Congress has
shown elsewhere in the same statute that it knows how to
make such a requirement manifest.” Jama v. Immigration
and Customs Enforcement, 543 U. S. 335, 341 (2005).
Rather than import language from one provision (subsection
(A)) into another that conspicuously omits that language
(subsection (B)), the Court should acknowledge that, natu-
rally read, subsection (B) is not broadened by language omit-
ted from it but included in the more expansive text of subsec-
tion (A).
IV
The Court also granted certiorari to decide whether a
“firear m” can “ i nclude a weapon par ts k it. ” 27 CFR
§ 478.11. Statutory text, context, and structure confrm that
this aspect of the Rule also exceeds the scope of the statute.
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Thomas, J., dissenting
The majority's novel artifact-noun methodology cannot alter
th
is conclusion.
A
Section 921(a)(3)(A)'s defnition of “frearm” includes “any
weapon” that “will or is designed to or may readily be con-
verted to expel a projectile by the action of an explosive.”
Thus, while an object that “may readily be converted” into a
gun qualifes as a “frearm” if that object is already a
“weapon,” an object that is not already a weapon does not.
The ordinary meaning of “weapon” does not include
weapon-parts kits. At the time of the GCA's enactment, the
word “weapon” was understood to mean “an instrument of
offensive or defensive combat . . . something to fght with . . .
something (as a club, sword, gun, or grenade) used in de-
stroying, defeating, or physically injuring an enemy.” Web-
ster's Third New International Dictionary 2589 (1966) (Web-
ster's); accord, ante, at 470. A weapon-parts kit is not a
weapon until it is converted into an operable gun. It is no
more “something to fght with,” Webster's 2589, than the
sort of “unformed block of metal” that the Rule expressly
exempts from regulation, see 27 CFR § 478.12(c). The oper-
able gun pictured in the majority opinion is “an instrument”
one may use in “combat.” The unfnished, inoperable kit
pieces are not. See ante, at 469 (images). Because these
pieces do not constitute a “weapon,” they do not ft within
subsection (A)'s statutory defnition.
Statutory text and context reinforce this conclusion, as
they indicate that the “weapon” contemplated in subsection
(A) must have a “frame or receiver”—precisely the parts of
a weapon that weapon-parts kits omit. Section 923, for ex-
ample, requires manufacturers to identify their frearms “by
means of a serial number engraved or cast on the receiver
or frame of the weapon,” § 923(i) (emphasis added), clearly
implying that any such “weapon” includes a “receiver or
frame.” Section 921 supports this reading by delimiting the
defnition of a “frearm” to “any weapon” convertible into a
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508 BONDI
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functional gun, and “the frame or receiver of any such
w
eapon,” §§ 921(a)(3)(A)–(B) (emphasis added). This provi-
sion again assumes that the “weapon” in subsection (A) has
a “frame or receiver.”
That “starter guns and disassembled rifes” are prototypi-
cal illustrations of things covered under § 921(a)(3)(A) that
nevertheless “are not yet ft for effective use in combat,”
ante, at 482, underscores this conclusion. Both starter guns
and disassembled rifes usually have functional frames or re-
ceivers. In contrast, the frames and receivers included in
weapon-parts kits are unfnished, inoperable, and so cannot
constitute frames or receivers under subsection (B). See
supra, at 497–502. Since “any weapon” must have an opera-
ble “frame or receiver,” § 921(a)(3)(B), a weapon-parts kit
cannot be a “weapon.” Accordingly, it cannot become a reg-
ulated “frearm” under § 921(a)(3)(A).
8
Further, although the FFA previously regulated “any part
or parts” of a gun, 52 Stat. 1250, Congress limited the GCA's
coverage to only two such parts: “the frame or receiver,”
§ 921(a)(3)(B). “Presumably, Congress singled out these
components for special treatment because of the special role
they play in constructing frearms.” Ante, at 465. We
should “presume that a legislature says in a statute what it
means and means in a statute what it says there.” Connect-
icut Nat. Bank v. Germain, 503 U. S. 249, 253–254 (1992).
The statute's broader context also suggests that weapon-
parts kits are not regulable “frearms.” Section 921(a)(3)
defnes “frearm” for all of Chapter 44. It follows that, “if
8
Of course, starter guns are deliberately not designed for combat. See
ante, at 471 (explaining that a starter gun “fres blanks, not bullets,” is used
“at sporting events, not in combat,” and typically requires “using a power
tool” to convert it into an operable weapon). Congress's parenthetical in-
clusion of “a starter gun” as “any weapon” is therefore best understood to
incorporate an outlier, “counterintuitive defnitio[n],” not to expand the
defnition of “weapon” to include other items outside its ordinary meaning.
Scalia & Garner 232; see Babbitt, 515 U. S., at 719 (Scalia, J., dissenting).
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Thomas, J., dissenting
[Chapter 44] is to be interpreted as a symmetrical and coher-
ent
regulatory scheme,” Gustafson v. Alloyd Co., 513 U. S.
561, 569 (1995), the term should to the extent possible receive
a consistent meaning. While it is not diffcult to envision
how weapons that can be immediately assembled might be
helpful “during and in relation to any crime of violence”
under § 924(c)—also part of Chapter 44—it is hard to imagine
how an unfnished weapon-parts kit requiring conversion
could be helpful. At minimum, this understanding would
seem to imply a crime “during ” which the criminal could
take some untold amount of time to convert his kit into a
functional gun before using it. That does not ft any crime
of violence with which I am familiar. Cf. Babbitt v. Sweet
Home Chapter, Committee for Great Ore., 515 U. S. 687, 722–
723 (1995) (Scalia, J., dissenting) (“[T]he Secretary's interpre-
tation of `harm' is wrong if it does not ft with the use of
`take' throughout the Act. And it does not”).
9
B
Holding otherwise, the majority reasons that, as a “thing
created by humans,” the term “weapon” may encompass not
only weapons that are “combat ready,” but also those that
are “disassembled,” and that the term thus captures weapon-
9
Section 924(c) is not the only provision in Chapter 44 that poses prob-
lems for a defnition of “frearm” that includes weapon-parts kits. Other
provisions make clear that a “frearm” is something that may be “un-
loaded.” See, e. g., § 926A. But, a weapon-parts kit cannot fre a bullet
prior to machining and assembly, so whether an unexpended bullet is pres-
ent in the kit's inoperable fring chamber or magazine is irrelevant. Chap-
ter 44 also makes clear that a “frearm” is an object one may “carry . . .
concealed.” § 926B. Unlike a functional gun, however, a kit is a collec-
tion of unfnished parts, screws, and jigs. See ante, at 469 (images). The
notions of concealed carry and open carry in the context of weapon-parts
kits are inapposite. And, while a person might use a functional gun to
“kil[ l]” another during the “commission of a crime” in a federal facility,
see §§ 930(b), (c), the lethality of an unfnished weapon-parts kit is no dif-
ferent from that of an “unformed block of metal” exempted under the
Rule, 27 CFR § 478.12(c).
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parts kits “[i]n the same way and for the same reason.”
An
te, at 471. The majority again conjures up the “artifact
noun” to support an interpretation that is incompatible with
our traditional methods of statutory construction. See
supra, at 506–509.
Unlike a disassembled frearm, a weapon-parts kit requires
more than merely assembling the parts to become a func-
tional gun. Special tools and an indeterminate amount of
time are required to convert an unfnished weapon-parts kit
into a functional weapon. Thus, even assuming that the or-
dinary meaning of “weapon” does not resolve whether the
term includes weapon-parts kits, at minimum the term
“weapon” cannot encompass weapon-parts kits in “the same
way” it covers disassembled frearms. Ante, at 471.
The majority also insists that the term “weapon” should
cover “some unfnished instruments of combat” like weapon-
parts kits because § 921(a)(3)(A) includes starter guns,
which, like weapon-parts kits, can be converted into func-
tional weapons. Ante, at 471. But, because a starter gun
does not ft within the ordinary meaning of “weapon,” Con-
gress's decision to expand that term to cover that one, spe-
cifc object does not imply that Congress intended the word
“weapon” to also cover other objects that are not already
weapons. See n. 8, supra.
And, both a disassembled rife and a starter gun are
“weapons” for the reason a weapon-parts kit is not: Disas-
sembled rifes and starter guns typically have functional
frames or receivers. See supra, at 508.
10
10
The majority observes that “not every `frearm' will be capable of im-
plicating every criminal law discussing frearms” because Congress
broadly defned the term “frearm” to include objects—like frames and
silencers—that fall outside that term's ordinary meaning. Ante, at 476.
But, as previously shown in the context of starter guns, see n. 8, supra,
Congress's decision to provide a statutory term with specifc “counterintu-
itive defnitions” does not license courts to reinterpret the term however
they see ft. Scalia & Garner 232. And, while the majority identifes
specifc frearms laws that can coherently apply to weapon-parts kits,
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Thomas, J., dissenting
V
The
text, context, and structure of § 921(a)(3) leave little
doubt that weapon-parts kits are not “frearms,” and that
the unfnished contents of these kits are neither “frame[s]”
nor “receiver[s].” But, even if it were reasonable to treat
artifact nouns differently, the Government would—at most—
demonstrate statutory ambiguity. And, when a statute with
criminal applications is ambiguous, the rule of lenity applies.
See Leocal v. Ashcroft, 543 U. S. 1, 12, n. 8 (2004).
This case is similar to United States v. Thompson/Center
Arms Co., 504 U. S. 505 (1992). There, a majority of the
Court applied the rule of lenity to interpret a tax statute
with criminal applications. That case presented the ques-
tion whether a gun manufacturer “makes” short-barreled ri-
fes—and is thus subject to the NFA's “making tax,” see 26
U. S. C. § 5821—by selling a pistol and conversion kit from
which one could make a short-barreled rife. See 504 U. S.,
at 507 (plurality opinion). After considering several argu-
ments—including analogies to products that “requir[e] some
home assembly,” and comparisons to terms referring to
“ `any combination of parts' ”—the plurality concluded that it
was “left with an ambiguous statute.” Id., at 509–517.
And, because the provision carried the threat of criminal
sanction, the plurality held that it was “proper . . . to apply
the rule of lenity and resolve the ambiguity in Thompson/
Center's favor.” Id., at 518.
Justice Scalia concurred in the judgment. Whereas the
plurality found ambiguity in the conversion kits' potential
ante, at 476, that overlap does not diminish the tensions I have described
above, see supra, at 508–509. Our job is to ensure a “coherent and con-
sistent” statutory scheme “to the extent possible.” Ali v. Federal Bureau
of Prisons, 552 U. S. 214, 222 (2008). That Congress's “capacious” defni-
tion of “frearm” already generates some tension in the statute, see ante,
at 476–477, is no reason to exacerbate that tension with a defnition that
makes Chapter 44 a less “symmetrical and coherent regulatory scheme,”
Gustafson v. Alloyd Co., 513 U. S. 561, 569 (1995).
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512 BONDI
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Thomas, J., dissenting
uses, he attributed the ambiguity to a “much more funda-
ment
al” question: “[W]hether the making of a regulated
frearm includes the manufacture, without assembly, of com-
ponent parts where the defnition of the particular frearm
does not so indicate.” Id., at 519. He found persuasive the
contrast between the defnition of regulated objects that ex-
pressly included “any combination of parts,” and those that
did not. See id., at 519–520 (noting that the provision at
issue “conspicuously combine[s] references to `combination of
parts' in the defnitions of regulated silencers, machineguns,
and destructive devices with the absence of any such refer-
ence in the defnition of regulated rifes”). Because neither
the defnition of “rife” nor that of “shortbarreled rife” incor-
porated combinations of parts, these distinctions made clear
that the NFA “d[id] not encompass Thompson/Center's pistol
and conversion kit, or at least d[id] not do so unambigu-
ously.” Ibid.
I would take Justice Scalia's approach here. Nothing in
the GCA suggests that the terms “frame” and “receiver” also
include the materials that one could use to create them,
or that parts including neither a frame nor a receiver could
constitute a “weapon.” See 18 U. S. C. §§ 921(a)(3)(A)–(B).
There are, however, many reasons to conclude the opposite.
See supra, at 497–510; cf. Thompson/Center, 504 U. S., at
519–520 (opinion of Scalia, J.).
Even the Government appears to have found these com-
peting interpretations persuasive just a few years ago. See
Brief for ATF 14, 36–39 (endorsing the position it now re-
jects). “Now it says the opposite. The law hasn't changed,
only an agency's interpretation of it.” Guedes v. ATF, 589
U. S. –––, ––– (2020) (statement of Gorsuch, J., respecting
denial of certiorari). I would apply the rule of lenity here.
***
Congress could have authorized ATF to regulate any part
of a frearm or any object readily convertible into one. But,

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as: 604 U. S. 458 (2025)
513
Alito, J., dissenting
it did not. I would adhere to the words Congress enacted.
Employ
ing its novel “artifact noun” methodology, the major-
ity charts a different course that invites unforeseeable conse-
quences and offers no limiting principle. I respectfully
dissent.
Justice Alito, dissenting.
The Court decides this case on a ground that was not
raised or decided below and that was not the focus of the
briefng or argument in this Court. Specifcally, the Court
concludes (1) that respondents mounted a “facial” challenge
to a Bureau of Alcohol, Tobacco, Firearms and Explosives
(ATF) rule implementing provisions of the Gun Control Act
of 1968, (2) that a party making such a challenge must meet
the test that applies when a statute is challenged as facially
unconstitutional (what I will call the Salerno test
1
), and (3)
that respondents cannot satisfy that demanding test.
2
If I
were satisfed that the Salerno test should control here, I
would join the opinion of the Court. The Court points to a
gun kit that is all-but-assembled, ante, at 468–469, and a frame
that is as close to completion as possible, ante, at 479–480. As
applied to those extreme situations, the Court holds—and I
agree—the rule does not deviate from the statute. But I
am not certain that the Salerno test should govern.
I
Respondents' petition for review in this case claimed,
among other things, that the ATF rule goes beyond what the
Gun Control Act permits and that it should therefore be “set
aside” under § 706(2) of the Administrative Procedure Act, 5
1
See United States v. Salerno, 481 U. S. 739, 745 (1987).
2
Under that test, “a plaintiff cannot succeed on a facial challenge unless
he establishes that no set of circumstances exists under which the law
would be valid, or he shows that the law lacks a plainly legitimate sweep.”
Moody v. NetChoice, LLC, 603 U. S. 707, 723 (2024) (alterations and inter-
nal quotation marks omitted).

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514 BONDI
v. VANDERSTOK
Alito, J., dissenting
U. S. C. § 706(2)(C). See Amended Petition for Review in No.
4:22
–cv–00691 (ND Tex.), ECF Doc. 93, pp. 41–42. In the
Fifth Circuit and other Courts of Appeals, that provision has
long been understood to permit a court to hold that a rule is
invalid in toto.
3
Thus, in both the District Court and the
Court of Appeals, the parties appear to have proceeded on
the assumption that the question presented was simply
whether the ATF rule exceeded the agency's authority under
the Gun Control Act. The Government defended the rule
as a correct interpretation of those statutory provisions and
made no mention of the Salerno test.
4
And for the most
part, that was the position advanced in the Government's
briefs in this Court. As the Court points out, however, one
paragraph of the Government's brief did make the Salerno
argument. See Brief for Petitioners 27–28. But other than
quoting language in INS v. National Center for Immigrants'
Rights, Inc., 502 U. S. 183, 188 (1991) (NCIR), the brief made
no effort to explain why that test should apply. And per-
haps because of this cursory treatment, none of the respond-
ents addressed the Salerno issue in their briefs or during
oral argument. Noting this silence, the Court regards the
applicability of the Salerno test as undisputed, and it then
proceeds to apply that test. Ante, at 467.
On the record here, I would not hold that respondents
agreed that the Salerno test should apply. The Court relies
on the use of the term “facial” in their complaints, but that
characterization of their challenges did not constitute agree-
ment with the proposition that a facial challenge to a regula-
3
See K. Mizelle, To Vacate or Not To Vacate: Some (Still) Unanswered
Questions in the APA Vacatur Debate, 2023 Harv. J. L. & Pub. Pol'y Per
Curiam 1, 3–4, and nn. 20–26.
4
See Brief for Appellants in VanDerStok v. Garland, No. 23–10718
(CA5), ECF Doc. 77–1, pp. 18–32; Defendants' Combined Brief in Opposi-
tion to Original Plaintiffs' and Intervenor-Plaintiffs' Motions for Summary
Judgment and in Support of Defendants' Cross-Motion for Summary Judg-
ment in Vanderstok v. Garland, No. 4:22–cv–00691 (ND Tex.), ECF Doc.
181, pp. 40–45.

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as: 604 U. S. 458 (2025)
515
Alito, J., dissenting
tion must satisfy the Salerno test. And in fact respondents
ne
ver conceded that point. They did not address the issue
at all in their briefs, and at no point during the lengthy oral
argument in this case were they asked about that question.
Holding that they conceded the point is unwarranted and ex-
tremely unfair. And in any event, we should adjudicate a
facial challenge under the right test regardless of the parties'
arguments. See Moody v. NetChoice, LLC, 603 U. S. 707,
779–780 (2024) (Alito, J., concurring in judgment).
II
That brings me to the question whether the Salerno test
should apply. In Moody, I set out what I saw as the chief
reasons for using that test when a statute is challenged as
unconstitutional. See 603 U. S., at 777–778 (opinion concur-
ring in judgment). One of the most important of these is
respect for the lawmaking authority of the legislative body
that enacted the law in question. Id., at 777. A law passed
by Congress or a State Legislature should not be held to be
entirely unenforceable just because it would be unconstitu-
tional to apply it in just a few situations. That would repre-
sent unjustifed judicial interference with the authority of
the body entrusted under the Federal Constitution or the
constitution of a State with the authority to make law.
This threat to legislative authority is not present when a
regulation is challenged. I recognize that two of our deci-
sions support the use of the Salerno test in cases involving
facial challenges to rules. See Reno v. Flores, 507 U. S. 292,
301 (1993); NCIR, 502 U. S., at 188. But neither decision
explained why the Salerno rule should be extended in that
way, and in neither case did the Court grapple with the ques-
tion that has recently arisen regarding the scope of a court's
authority under § 706(2) of the APA.
Applying the Salerno rule in a case in which a rule is
challenged under that provision as exceeding the agency's
statutory authority may have far-reaching consequences.
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516 BONDI
v. VANDERSTOK
Alito, J., dissenting
As a commentator has observed, “Salerno would seem to
dic
tate that a plaintiff [who challenges a rule] cannot ever
win unless he can show that there is `no set of circumstances'
in which the regulation would be consistent with the statute.
And because it would take an extraordinarily obtuse agency
to write a regulation so completely wrong as that, applying
Salerno in the statutory context would seem to dictate that
plaintiffs would always lose.” S. Buck, Salerno vs. Chevron:
What To Do About Statutory Challenges, 55 Admin. L. Rev.
427, 438 (2003). Thus, this extension of Salerno would rep-
resent a huge boon for the administrative state.
It would also all but settle the debate about whether
§ 706(2) of the APA authorizes a court to render a rule unen-
forceable across the board.
5
Respondents asserted a typical
claim seeking to have a rule “set aside” in its entirety under
§ 706(2), and if that claim fails because there are at least some
situations in which the application of the rule would be law-
ful, then it seems to follow that virtually all such claims will
fail as well. The understanding of the “set-aside” power
that has long been prevalent in the courts of appeals will be
overturned, and parties who may be adversely affected by a
rule will be reduced to fling as-applied challenges. Perhaps
that is what the law calls for, but we should not effect such
a change without thorough briefng and argument.
For these reasons, I must respectfully dissent. I would
either direct the parties to brief the Salerno issue or vacate
the judgment below and remand so that the issue can be
addressed frst by the Court of Appeals.
6
5
Compare J. Harrison, Vacatur of Rules Under the Administrative Pro-
cedure Act, 40 Yale J. on Reg. 119, 120 (2023) (arguing that the APA does
not confer that power), with M. Sohoni, The Power To Vacate a Rule, 88
Geo. Wash. L. Rev. 1121, 1122, 1126 (2020) (taking the opposite position);
see also Mizelle, 2023 Harv. J. L. & Pub. Pol'y, at 2–10 (summarizing the
debate).
6
Justice Sotomayor's suggestion that I have mischaracterized what
the Court has held, ante, at 486 (concurring opinion), demands a response.
Although Justice Sotomayor obviously wishes that the Court had gone

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as: 604 U. S. 458 (2025)
517
Alito, J., dissenting
further, all that the Court has actually held is that the ATF rule is not
facially invalid because at least some applications of the rule are consistent
with the statute. And the two examples that the Court cites are (1) a kit
that contains all the parts needed to make a semiautomatic pistol and that
can be assembled in 21 minutes, see ante, at 468–473, and (2) a frame that
can be made functional simply by clipping off two plastic tabs and drilling
a few holes, ante, at 477–479, 481. The Court has not held that any other
kits or presently non-functional receivers are covered.
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Reporter’s Note
The attached opinion has been revised to refect the usual publication
and citation style of the United States Reports. The revised pagination
makes available the offcial United States Reports citation in advance of
publication. The syllabus has been prepared by the Reporter of Decisions
for the convenience of the reader and constitutes no part of the opinion of
the Court. A list of counsel who argued or fled briefs in this case, and
who were members of the bar of this Court at the time this case was
argued, has been inserted following the syllabus. Other revisions may
include adjustments to formatting, captions, citation form, and any errant
punctuation. The following additional edits were made:
p. 470, line 8: “English” is deleted
p. 470, line 8: “of Current English” is inserted after “Dictionary
p. 475, line 2: “kits” is deleted
p. 493, line 10: “VanDerStok v. Garland,” is inserted before 680
p. 493, line 11: “VanDerStok v. Garland,” is inserted before 86
p. 504, line 9: “frearm” is inserted before “silencer”