Court Opinion

ID: 5134953
Source: CourtListenerOpinion
Date Created: 2021-12-15 01:00:57.399445+00
Date Added: 2024-06-11T08:23:46.355785
License: Public Domain

Case: 20-51016    Document: 00516130656        Page: 1    Date Filed: 12/14/2021

           United States Court of Appeals
                for the Fifth Circuit                            United States Court of Appeals
                                                                          Fifth Circuit

                                                                        FILED
                                                                December 14, 2021
                                No. 20-51016
                                                                   Lyle W. Cayce
                                                                        Clerk
   Michael Cargill,

                                                         Plaintiff—Appellant,

                                    versus

   Merrick Garland, U.S. Attorney General; United
   States Department of Justice; Regina Lombardo, in her
   official capacity as Acting Director of the Bureau of
   Alcohol, Tobacco, Firearms, and Explosives; Bureau of
   Alcohol, Tobacco, Firearms, and Explosives,

                                                     Defendants—Appellees.

                 Appeal from the United States District Court
                      for the Western District of Texas
                           USDC No. 1:19-CV-349

   Before Dennis, Higginson, and Costa, Circuit Judges.
   Stephen A. Higginson, Circuit Judge:
         On October 1, 2017, a gunman firing several semiautomatic rifles
   equipped with bump stocks killed 58 people and wounded 500 more in Las
   Vegas. In the aftermath of this tragedy, the Bureau of Alcohol, Tobacco,
   Firearms and Explosives (“ATF”) promulgated a rule (the “Bump Stock
   Rule” or “Rule”) stating that bump stocks are “machinegun[s]” for
   purposes of the National Firearms Act (“NFA”) and the federal statutory
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                                          No. 20-51016

   bar on the possession or sale of new machine guns. 1 Bump-Stock-Type Devices,
   83 Fed. Reg. 66,514 (Dec. 26, 2018); see also 18 U.S.C. §§ 922(o)(1),
   921(a)(23); 26 U.S.C. § 5845(b). Plaintiff-Appellant Michael Cargill has
   challenged the Rule, arguing that it contradicts the plain language of the
   statute, that it exceeds ATF’s statutory authority, and that it violates the
   separation of powers. After a trial, the district court rejected Cargill’s claims,
   concluding in a 75-page order that the Rule “properly classifies a bump stock
   as a ‘machinegun’ within the statutory definition.” Because we agree with
   the district court that bump stocks qualify as machine guns under the best
   interpretation of the statute, we AFFIRM. 2

           1
               Except when quoting sources, we use the two-word spelling of “machine gun.”
           2
              Three other circuits have also rejected challenges to the Bump Stock Rule. In
   April 2019, the D.C. Circuit denied a motion for a preliminary injunction against the Rule,
   concluding that the statutory definition of “machinegun” is ambiguous and that the Rule
   is entitled to Chevron deference. Guedes v. Bureau of Alcohol, Tobacco, Firearms & Explosives,
   920 F.3d 1 (D.C. Cir. 2019) (per curiam). One judge dissented, arguing that the Rule
   contradicts the statute’s plain language. Id. at 35 (Henderson, J., dissenting). The Supreme
   Court denied certiorari, 140 S. Ct. 789 (2020), though Justice Gorsuch issued a statement
   arguing that the Rule is not entitled to Chevron deference. Id. at 789-91 (Gorsuch, J.,
   statement regarding denial of certiorari). In May 2020, the Tenth Circuit denied another
   motion to preliminarily enjoin the Rule, for similar reasons as the D.C. Circuit. Aposhian v.
   Barr, 958 F.3d 969 (10th Cir. 2020). Four months later, the Tenth Circuit vacated that
   opinion and granted a rehearing en banc, 973 F.3d 1151 (10th Cir. 2020) (en banc), but it
   subsequently reversed course, vacating the order granting rehearing en banc and reinstating
   the original panel opinion. Aposhian v. Wilkinson, 989 F.3d 890 (10th Cir. 2021) (en banc).
   Five judges dissented from the decision to vacate the en banc order. Id. at 891 (Tymkovich,
   C.J. dissenting, joined by Hartz, Holmes, Eid, and Carson, JJ.). The plaintiff in that case
   has filed a petition for certiorari in the Supreme Court. Petition for Writ of Certiorari,
   Aposhian v. Garland, No. 21-159 (U.S. Aug. 4, 2021). Finally, in March 2021, a Sixth Circuit
   panel granted a preliminary injunction against the Rule, holding that the Rule is not entitled
   to Chevron deference and is not the best interpretation of the NFA. Gun Owners of Am., Inc.
   v. Garland, 992 F.3d 446, 450 (6th Cir. 2021). However, the Sixth Circuit vacated that
   decision, 2 F.4th 576 (6th Cir. 2021) (en banc), and an evenly divided en banc court
   affirmed the district court’s judgment upholding the Rule. No. 19-1298, --- F.4th ----, 2021

                                                 2
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                                              I.
                                              A.
           Federal law generally makes it “unlawful for any person to transfer or
   possess a machinegun.” 18 U.S.C. § 922(o)(1). The federal machine gun ban
   incorporates the NFA’s definition of “machinegun,” 18 U.S.C. § 921(a)(23),
   which reads as follows:
           The term “machinegun” means any weapon which shoots, is
           designed to shoot, or can be readily restored to shoot,
           automatically more than one shot, without manual reloading,
           by a single function of the trigger. The term shall also include
           the frame or receiver of any such weapon, any part designed
           and intended solely and exclusively, or combination of parts
           designed and intended, for use in converting a weapon into a
           machinegun, and any combination of parts from which a
           machinegun can be assembled if such parts are in the
           possession or under the control of a person.
   26 U.S.C. § 5845(b).
           Congress has vested in the Attorney General authority to prescribe
   rules and regulations necessary to enforce the NFA and the federal machine
   gun ban. See 18 U.S.C. § 926(a); 26 U.S.C. §§ 7801(a)(2)(A), 7805(a). The
   Attorney General has delegated this responsibility to ATF. See 28 C.F.R.
   § 0.130(a)(1)-(2).
                                              B.
           As the district court found, a “bump stock” is “an accessory attached
   to a firearm to increase its rate of fire, to make it easier for somebody to fire a
   weapon faster.” More specifically, bump stocks are devices that “harness the

   WL 5755300 (6th Cir. Dec. 3, 2021) (en banc); see Gun Owners of Am. v. Barr, 363 F. Supp.
   3d 823, 826 (W.D. Mich. 2019).

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   force of recoil to enable a weapon to fire multiple rounds when, while keeping
   the trigger finger stationary, the shooter pushes forward with the non-
   shooting hand.” These devices generally consist of “a sliding shoulder stock
   molded or otherwise attached to a grip,” “a ‘trigger ledge,’ on which the
   shooter places his finger,” and “a detachable rectangular receiver module
   that goes in the receiver well of the bump stock’s handle to guide the recoil
   of the weapon when fired.” The “firing sequence” of a semiautomatic rifle
   equipped with a bump stock “begins when the shooter presses forward on
   the firearm to initially engage the trigger finger.” The gun then “slides back
   and forth[,] and its recoil energy bumps the trigger finger into the trigger to
   continue firing until the shooter stops pushing forward with his non-shooting
   hand or the weapon runs out of ammunition or malfunctions.” (emphasis
   added). Thus, “when a bump stock is used as intended, the shooter pushes
   forward to engage the trigger finger with the trigger, which causes a single
   trigger pull that initiates a firing sequence that continues to fire as long as the
   shooter continues to push forward.” See also 83 Fed. Reg. at 66,516
   (“Shooters use bump-stock-type devices with semiautomatic firearms to
   accelerate the firearms’ cyclic firing rate to mimic automatic fire.”).
          Prior to the 2017 mass shooting in Las Vegas, ATF had maintained
   that bump stocks that did not use internal springs, such as the device used in
   the Las Vegas shooting, were not machine guns for purposes of federal law.
   83 Fed. Reg. at 66,516. However, after the Las Vegas shooting, ATF decided
   to reconsider that position, and it issued an advance notice of proposed
   rulemaking in December 2017. Application of the Definition of Machinegun to
   “Bump Fire” Stocks and Other Similar Devices, 82 Fed. Reg. 60,929 (Dec. 26,
   2017). Shortly thereafter, then-President Donald Trump issued a
   memorandum instructing the Department of Justice “to propose for notice
   and comment a rule banning all devices that turn legal weapons into
   machineguns.” Application of the Definition of Machinegun to “Bump Fire”

                                           4
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   Stocks and Other Similar Devices, 83 Fed. Reg. 7,949, 7,949 (Feb. 20, 2018).
   ATF issued a notice of proposed rulemaking in March 2018, Bump-Stock
   Devices, 83 Fed. Reg. 13,442 (Mar. 29, 2018), and, after receiving more than
   186,000 comments, promulgated a final rule in December 2018. 83 Fed. Reg.
   at 66,514, 66,519. 3
           The Bump Stock Rule interprets the NFA’s above-quoted definition
   of “machinegun.” See 26 U.S.C. § 5845(b). The Rule states:
           For purposes of this definition, the term “automatically” as it
           modifies “shoots, is designed to shoot, or can be readily
           restored to shoot,” means functioning as the result of a self-
           acting or self-regulating mechanism that allows the firing of
           multiple rounds through a single function of the trigger; and
           “single function of the trigger” means a single pull of the
           trigger and analogous motions.
   83 Fed. Reg. at 66,553 (codified at 27 C.F.R. §§ 447.11, 478.11, 479.11). Based
   on this interpretation of the terms “automatically” and “single function of
   the trigger,” the Rule concludes that the “term ‘machinegun’ includes a
   bump-stock-type device,” since bump stocks enable “a semi-automatic
   firearm to shoot more than one shot with a single pull of the trigger by
   harnessing the recoil energy of the semi-automatic firearm to which it is
   affixed so that the trigger resets and continues firing without additional
   physical manipulation of the trigger by the shooter.” Id. at 66,553-54.

           3
             The Bump Stock Rule was signed by Acting Attorney General Matthew G.
   Whitaker. Id. at 66,554. Subsequently, parties challenging the rule argued that Whitaker
   had not been validly serving as Acting Attorney General. Bump-Stock-Type Devices, 84 Fed.
   Reg. 9,239, 9,240 (March 14, 2019). To resolve any uncertainty about the Rule’s
   legitimacy, newly-sworn-in Attorney General William Barr issued a statement in March
   2019 saying that he had evaluated “the rulemaking record” and “personally come to the
   conclusion that it is appropriate to ratify and affirm the [Rule].” Id.

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          By its own terms, the Rule became “effective” on March 26, 2019,
   ninety days after its promulgation. Id. at 66,514. The Rule explains that
   “individuals are subject to criminal liability only for possessing bump-stock-
   type devices after the effective date of regulation,” and it instructs bump
   stock owners to either “undertake destruction of the devices” or “abandon
   [them] at the nearest ATF office.” Id. at 66,525, 66,530.
                                         C.
          Following the issuance of the Bump Stock Rule, Michael Cargill
   surrendered two bump stocks to ATF. He then sued ATF under the
   Administrative Procedure Act and various constitutional provisions, seeking
   a declaratory judgment and permanent injunction preventing the
   enforcement of the Bump Stock Rule against him and others similarly
   situated, along with the return of his bump stocks.
          After holding a bench trial, the district court denied Cargill’s
   requested relief on all counts. The court first determined that ATF had
   statutory authority to issue the Bump Stock Rule and that the Rule did not
   violate the constitutional principles of non-delegation and separation of
   powers. The court then concluded that the Bump Stock Rule adopts the
   “correct” interpretation of the terms “automatically” and “single function
   of the trigger.” Accordingly, the court held that the Rule “properly classifies
   a bump stock as a ‘machinegun’ within the statutory definition.” Cargill
   timely filed this appeal.
                                         II.
          We first consider the statutory interpretation issue. Recall that, for
   purposes of federal law, “[t]he term ‘machinegun’ means any weapon which
   shoots . . . automatically more than one shot, without manual reloading, by a
   single function of the trigger,” including “any part designed and intended
   solely and exclusively, or combination of parts designed and intended, for use

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   in converting a weapon into a machinegun.” 26 U.S.C. § 5845(b). Cargill
   argues that the Bump Stock Rule’s conclusion that bump stocks qualify as
   “machinegun[s]”          under     this     definition     contradicts     the    statute’s
   unambiguous terms. Cargill further argues that even if the statute is
   ambiguous, the rule of lenity requires the court to resolve any ambiguity in
   his favor. The district court rejected these arguments, concluding that the
   “Rule adopts the proper interpretation of ‘machinegun’ by including bump
   stock devices” and that “the rule of lenity does not apply.” We agree with
   the district court’s conclusions. 4
                                                A.
           Cargill    argues      that     bump      stocks    unambiguously        are    not
   “machinegun[s]”          under        the   above      statutory    definition     because
   semiautomatic firearms equipped with bump stocks (1) do not shoot “more
   than one shot . . . by a single function of the trigger” and (2) do not shoot
   “automatically.” We consider each of these points in turn.
                                                1.
           Cargill argues that bump stock-equipped semiautomatic rifles do not
   shoot “more than one shot . . . by a single function of the trigger” because
   the trigger of such weapons must mechanically “reset” before the gun can

           4
              Cargill also argues that if the statute is ambiguous, the Bump Stock Rule is not
   entitled to deference under Chevron, U.S.A., Inc. v. Natural Resources Defense Council, Inc.,
   467 U.S. 837 (1984), reasoning primarily that Chevron does not apply to cases involving
   criminal statutes and that ATF explicitly waived Chevron in the district court. Because we
   conclude that bump stocks are “machinegun[s]” under the best interpretation of the
   statute, we do not address whether the Rule is entitled to deference. See Edelman v.
   Lynchburg Coll., 535 U.S. 106, 114 (2002) (explaining that “there is no occasion to defer
   and no point in asking what kind of deference, or how much” would apply in cases where
   an agency has adopted “the position we would adopt even if there were no formal rule and
   we were interpreting the statute from scratch”).

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   “fire the next shot.” Cargill thus appears to interpret the phrase “single
   function of the trigger” to mean “a single mechanical act of the trigger” or
   perhaps “a single movement of the trigger.” On the other hand, the Bump
   Stock Rule provides that “‘single function of the trigger’ means a single pull
   of the trigger and analogous motions.” 83 Fed. Reg. at 66,553.
           The Rule’s interpretation of the statutory phrase proves compelling.
   Both the Supreme Court and this court have replaced the word “function”
   with “pull” when paraphrasing the NFA’s definition of “machinegun.” See
   Staples v. United States, 511 U.S. 600, 602 n.1 (1994) (observing that the NFA
   treats a weapon that “fires repeatedly with a single pull of the trigger” as a
   machinegun, in contrast to a “weapon that fires only one shot with each pull
   of the trigger”); United States v. Anderson, 885 F.2d 1248, 1250 (5th Cir.
   1989) (en banc) (explaining that “fully automatic pistols . . . qualify as
   ‘machine guns’” under the NFA because “they will fire more than one
   round of ammunition in response to a single pull of the trigger”). 5 Indeed, at
   the time the statute was enacted, the two terms were used almost
   interchangeably in the context of firearms. See H.R. Rep. No. 73-1780, at 2
   (1934) (explaining that the NFA “contains the usual definition of machine
   gun as a weapon designed to shoot more than one shot without reloading and
   by a single pull of the trigger”); National Firearms Act: Hearings on H.R. 9066
   Before the H. Comm. On Ways & Means, 73d Cong. 40 (1934) [hereinafter
   NFA Hearings] (statement of Karl T. Frederick, President, National Rifle
   Association of America) (“A gun . . . which is capable of firing more than one
   shot by a single pull of the trigger, a single function of the trigger, is properly

           5
             See also Guedes v. Bureau of Alcohol, Tobacco, Firearms, & Explosives, 356 F. Supp.
   3d 109, 130 (D.D.C.), aff’d, 920 F.3d 1 (D.C. Cir. 2019), cert. denied, 140 S. Ct. 789 (2020)
   (“Tellingly, courts have instinctively reached for the word ‘pull’ when discussing the
   statutory definition of ‘machinegun.’” (citing Staples, 511 U.S. at 602 n.1; United States v.
   Oakes, 564 F.2d 384, 388 (10th Cir. 1977)).

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   regarded, in my opinion, as a machine gun.”). Accordingly, in a case
   involving a predecessor rule to the Bump Stock Rule, the Eleventh Circuit
   expressly held that ATF’s “interpretation . . . that the phrase ‘single
   function of the trigger’ means a ‘single pull of the trigger’ is consonant with
   the statute.” Akins v. United States, 312 F. App’x 197, 200 (11th Cir. 2009)
   (unpublished) (citing Staples, 511 U.S. at 602 n.1; NFA Hearings at 40). This
   caselaw and contemporary usage reflect a simple fact undergirding the Rule’s
   interpretation of the statute—in ordinary English, firearm triggers typically
   “function” by means of a shooter’s “pull.” 6
           The Chief Judge of the Tenth Circuit makes perhaps the strongest
   case that the NFA defines “machinegun” in terms of a trigger’s mechanical
   acts. Writing in dissent, he argues that the “statute’s plain language makes
   clear the ‘function’ must be ‘of the trigger.’ The statute speaks only to how
   the trigger acts, making no mention of the shooter.” Aposhian v. Wilkinson,
   989 F.3d 890, 895 (10th Cir. 2021) (Tymkovich, C.J., dissenting from
   vacation of order granting rehearing en banc) (citation omitted). He
   continues:
           The trigger on [a semiautomatic rifle equipped with a bump
           stock] must necessarily “pull” backwards and release the
           rifle’s hammer every time that the rifle discharges. The rifle
           cannot fire a second round until both the trigger and hammer
           reset. Every shot requires the trigger to go through this full
           process again. The fact that a bump stock accelerates this

           6
             See, e.g., Oliver Wendell Holmes, Jr., The Common Law:
   Lecture IV 149-50 (1881) (explaining that “[t]he ordinarily intelligent and prudent
   member of the community would foresee the possibility of danger from pointing a gun
   which he had not inspected into a crowd, and pulling the trigger, although it was said to be
   unloaded”).

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          process does not change the underlying fact that it requires
          multiple functions of the trigger to mimic a machine gun.
   Id. (cleaned up).
          We considered a similarly mechanistic interpretation of § 5854(b) in
   United States v. Camp. That case involved a firearm that operated as follows:
          When an added switch behind the original trigger was pulled,
          it supplied electrical power to a motor connected to the bottom
          of a fishing reel that had been placed inside the weapon’s
          trigger guard; the motor caused the reel to rotate; and that
          rotation caused the original trigger to function in rapid
          succession.
   343 F.3d 743, 744 (5th Cir. 2003). The gunowner argued that because the
   “original trigger . . . functioned each time the rifle was fired, the rifle, as
   modified, did not become a machine gun.” Id. at 745. “The switch,” he
   averred, “is merely a legal ‘trigger activator.’” Id. However, we held that
   because the modified weapon “required only one action—pulling the switch
   [the gunowner] installed—to fire multiple shots,” the weapon “shoot[s]
   automatically more than one shot . . . by a single function of the trigger.” Id.
   (third alteration in original) (quoting 26 U.S.C. § 5845(b)). To hold
   otherwise, we explained, “would allow transforming firearms into machine
   guns, so long as the original trigger was not destroyed.” Id.
          Our court thus rejected a mechanistic interpretation of § 5845(b) in
   Camp. We likewise decline to adopt a mechanistic reading of the statute, for
   several reasons in addition to the precedent set by Camp. As an initial matter,
   the mechanistic interpretation of the NFA twists the statutory text,
   effectively rewriting the statute to make “function” a verb that has “trigger”
   as its subject—that is, rewriting the statute so that it defines a “machinegun”
   as a weapon which shoots more than one shot “every time the trigger
   functions” rather than “by a single function of the trigger.” Moreover,

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   interpreting the NFA mechanistically defies common sense. As one district
   court has observed, there is no reason why “Congress would have zeroed in
   on the mechanistic movement of the trigger in seeking to regulate automatic
   weapons,” given that the “ill sought to be captured by this definition was the
   ability to drastically increase a weapon’s rate of fire, not the precise
   mechanism by which that capability is achieved.” Aposhian v. Barr, 374 F.
   Supp. 3d 1145, 1152 (D. Utah 2019), aff’d, 958 F.3d 969 (10th Cir. 2020),
   petition for cert. filed sub nom. Aposhian v. Garland, No. 21-159 (U.S. Aug. 4,
   2021). Congress likely chose the term “function” not to emphasize the
   mechanical working of the trigger but rather because it has a broader meaning
   than “pull,” in order “to forestall attempts by weapon manufacturers or
   others to implement triggers that need not be pulled, thereby evading the
   statute’s reach.” Id. 7 Finally, the mechanistic interpretation of the statute
   does not account for the above-discussed arguments relating to prior judicial
   interpretations and ordinary usage. For these reasons, ATF’s interpretation
   of the statute is the best interpretation. The phrase “single function of the
   trigger,” as used in the NFA, means “a single pull of the trigger and
   analogous motions.”
           Accordingly, Cargill’s argument that semiautomatic firearms
   equipped with bump stocks do not shoot “more than one shot . . . by a single
   function of the trigger” fails. As explained above, the district court found that
   “when a bump stock is used as intended, the shooter pushes forward to

           7
             To that end, ATF defined “single function of the trigger” as “a single pull of the
   trigger and analogous motions,” 83 Fed. Reg. at 66,553 (emphasis added), recognizing “that
   there are other methods of initiating an automatic firing sequence that do not require a
   pull.” Id. at 66,515. ATF encourages gun manufacturers to submit novel weapons and
   devices to the agency so that the agency can inform manufacturers in advance of production
   whether it considers the weapon or device to be a machine gun. See ATF, U.S. Dep’t of
   Justice, National Firearms Act Handbook 41 (Apr. 2009).

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   engage the trigger finger with the trigger, which causes a single trigger pull
   that initiates a firing sequence that continues to fire as long as the shooter
   continues to push forward.” 8 Or in the words of the Rule, “when a shooter
   who has affixed a bump-stock-type device to a semiautomatic firearm pulls
   the trigger, that movement initiates a firing sequence that produces more
   than one shot.” 83 Fed. Reg. at 66,519. Because bump stocks thus allow a
   shooter to shoot more than one shot by a single pull of the trigger, they allow
   a shooter to shoot “more than one shot . . . by a single function of the trigger.”
   26 U.S.C. § 5845(b).
                                               2.
           Cargill further argues that because the shooter must “push the barrel
   shroud forward with the non-trigger hand into the trigger against the gun’s
   recoil after every shot,” semiautomatic weapons equipped with bump stocks
   do not fire “automatically.” Cargill thus appears to interpret the term
   “automatically” to mean “completely without manual input.” On the other
   hand, the Bump Stock Rule provides that the term “automatically,” as used
   in the statutory definition of “machinegun,” “means functioning as the
   result of a self-acting or self-regulating mechanism that allows the firing of
   multiple rounds through a single function of the trigger.” 83 Fed. Reg. at
   66,553.
           Once again, the Rule offers a compelling interpretation of the statute.
   “We often look to dictionary definitions for help in discerning a word’s
   ordinary meaning.” Cascabel Cattle Co., L.L.C. v. United States, 955 F.3d 445,
   451 (5th Cir. 2020). According to one leading dictionary from 1934, the year

           8
            Importantly, after initiating the firing sequence in this manner, the “shooter does
   not have to pull rearward to continue firing as long as he keeps his finger on the trigger
   ledge.” Indeed, the district court quoted an expert as testifying that “the trigger finger
   ‘could be replaced by a post and would function the same way.’”

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   the NFA was enacted, “automatically” is the adverbial form of “automatic,”
   which in turn means “[h]aving a self-acting or self-regulating mechanism that
   performs a required act at a predetermined point in an operation.”
   WEBSTER’S NEW INTERNATIONAL DICTIONARY 187 (2d ed. 1934).
   Another dictionary from the time defines “automatic” as “[s]elf-acting
   under conditions fixed for it, going of itself.” OXFORD ENGLISH
   DICTIONARY 574 (1933). Relying on these definitions, the Seventh Circuit
   has explained that for purposes of the NFA, “the adverb ‘automatically’ . . .
   delineates how the discharge of multiple rounds from a weapon occurs: as the
   result of a self-acting mechanism” which “is set in motion by a single
   function of the trigger and is accomplished without manual reloading.”
   United States v. Olofson, 563 F.3d 652, 658 (7th Cir. 2009). As a nearly word-
   for-word copy of the dictionary definition that accords with past judicial
   interpretation, the Rule’s interpretation of “automatically” is the best
   interpretation of that term. 9
           The Chief Judge of the Tenth Circuit again makes the strongest case
   against the Rule’s interpretation of the statute. He argues that it is a mistake
   to “abstract[] ‘automatically’ from the rest of the statutory language.”
   Aposhian, 989 F.3d at 896 (Tymkovich, C.J., dissenting). After all, “[t]he
   statute is unambiguous about what makes the firearm shoot automatically:
   the function of the trigger.” Id. Accordingly, “[i]f a single function of the
   trigger and then some other input is required to make the firearm shoot
   automatically, we are not talking about a ‘machinegun’ as defined
   in § 5845(b).” Id. And, he explains, bump stocks require this extra input:
           [I]f a shooter pulls the trigger of a semiautomatic rifle equipped
           with a non-mechanical bump stock without doing anything

           9
             Indeed, the Rule explicitly relied on these dictionary definitions and the Seventh
   Circuit’s Olofson opinion when interpreting “automatically.” See 83 Fed. Reg. at 66,519.

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          else, the rifle will fire just one shot. . . . To make the firearm
          “shoot automatically more than one shot”, the shooter must
          also be pulling forward on the barrel of the gun. Because a bump
          stock requires this extra physical input, it does not fall within
          the statutory requirement that the weapon shoot
          “automatically . . . by a single function of the trigger.”
   Id. (citations omitted).
          Though not unreasonable on its face, the claim that a weapon does not
   fire “automatically” if it requires any manual input from the shooter beyond
   a single pull of the trigger in order to fire more than one shot ultimately
   proves too much. True, a shooter firing a semiautomatic firearm equipped
   with a bump stock generally must maintain “constant forward pressure with
   the non-trigger hand on the barrel-shroud or fore-grip of the rifle.” 83 Fed.
   Reg. at 66,516. However, as the district court explained, a prototypical
   machine gun requires the shooter to “keep constant pressure on the trigger
   with his shooting hand’s trigger finger.” Cargill offers no reason why
   firearms that require the shooter to maintain pressure on the trigger function
   “automatically” but firearms that require the shooter to maintain pressure
   on the barrel of the gun do not. Accordingly, we reject this interpretation of
   the statute. A firearm functions “automatically” as long as it “function[s] as
   the result of a self-acting or self-regulating mechanism that allows the firing
   of multiple rounds through a single function of the trigger,” 83 Fed. Reg. at
   66,553, regardless of whether a shooter must maintain pressure on the
   weapon while firing.
          Recall that the district court found that after a shooter pulls the trigger
   of a bump stock-equipped semiautomatic rifle to initiate the weapon’s firing
   sequence, the gun “slides back and forth[,] and its recoil energy bumps the
   trigger finger into the trigger to continue firing until the shooter stops
   pushing forward with his non-shooting hand or the weapon runs out of

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                                     No. 20-51016

   ammunition or malfunctions.” The district court further found, based on
   expert testimony, that “even though the shooter’s finger disengages and re-
   engages with the trigger during the bump firing process, the sequence set in
   motion by the initial forward pressure causing a trigger pull continues.
   Multiple rounds fire because ‘[t]he weapon recoils faster than you can
   react.’” Or as the Rule itself explains, a bump stock “harness[es] the recoil
   energy of the semi-automatic firearm to which it is affixed so that the trigger
   resets and continues firing without additional physical manipulation of the
   trigger by the shooter.” 83 Fed. Reg. at 66,553-54. For these reasons,
   semiautomatic firearms equipped with bump stocks shoot “as the result of a
   self-acting or self-regulating mechanism that allows the firing of multiple
   rounds through a single function of the trigger”—in other words, they shoot
   “automatically” for purposes of the statute. 26 U.S.C. § 5845(b).
                                         B.
          Cargill argues that even if the statutory text is ambiguous, ATF’s
   interpretation of the NFA is invalid because the court must resolve any
   ambiguity in this criminal statute in his favor under the rule of lenity. See
   Yates v. United States, 574 U.S. 528, 547-48 (2015) (“[A]mbiguity concerning
   the ambit of criminal statutes should be resolved in favor of lenity.”).
   However, “the rule of lenity only applies if, after considering text, structure,
   history, and purpose, there remains a grievous ambiguity or uncertainty in
   the statute such that the [c]ourt must simply guess as to what Congress
   intended.” Maracich v. Spears, 570 U.S. 48, 76 (2013) (quoting Barber v.
   Thomas, 560 U.S. 474, 488 (2010)). Here, for the reasons explained above,
   the traditional tools of statutory interpretation make it clear that the Bump
   Stock Rule’s interpretation of the NFA’s definition of “machinegun” is the

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                                          No. 20-51016

   best interpretation of the statute. Because no “grievous ambiguity or
   uncertainty” remains, id., the rule of lenity does not apply to this case. 10
                                            * * *
           A bump stock is “a part designed and intended” to enable a person
   armed with a semiautomatic rifle to “shoot[] . . . automatically more than one
   shot, without manual reloading, by a single function of the trigger.” 26
   U.S.C. § 5845(b). Accordingly, we agree with the district court that the
   Bump Stock Rule properly classifies bump stocks as “machinegun[s]” for
   purposes of federal law. Id.; see also 18 U.S.C. § 921(a)(23). 11
                                               III.
           Cargill argues that ATF exceeded its statutory authority by issuing the
   Bump Stock Rule. Cargill further argues that even if the agency had statutory
   authority to issue the Rule, the Rule violates the constitutional principle of
   separation of powers. The district court concluded that Congress had

           10
              Though the district court concluded that “the traditional tools of statutory
   interpretation yield unambiguous meanings” for the disputed terms, we hold only that the
   statute does not contain the kind of grievous ambiguity that causes the rule of lenity to
   apply.
           11
              Though we conclude that the Bump Stock Rule offers the best interpretation of
   the NFA’s definition of “machinegun,” Congress may wish to further clarify whether
   various novel devices qualify as machine guns for purposes of federal law. In accordance
   with the statutory opinion transmission project, our Opinion Clerk will notify Congress that
   this opinion “bears on technical matters of statutory construction.” See Robert A.
   Katzmann & Russell R. Wheeler, A Mechanism for “Statutory Housekeeping”: Appellate
   Courts Working with Congress, 9 J. App. Prac. & Process 131 (2007) (describing the
   history and purpose of the statutory opinion transmission project); Marin K. Levy & Tejas
   N. Narechania, Interbranch Information Sharing: Examining the Statutory Opinion
   Transmission Project, 108 Cal. L. Rev. 917, 921 (2020) (encouraging “federal appellate
   judges to send more opinions to Congress”).

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                                            No. 20-51016

   delegated authority to ATF to issue a rule like the Bump Stock Rule and that
   this Congressional delegation does not violate the separation of powers.
            We do not address these issues. As explained above, the Bump Stock
   Rule’s interpretation of the NFA’s definition of “machinegun” is the best
   interpretation of the statute. Accordingly, resolution of these issues will not
   affect the outcome of the case—either way, bump stocks are
   “machinegun[s]” and thus illegal under federal law. 18 U.S.C. § 922(o)(1).
   And because Cargill’s ability to own a bump stock would not change even if
   his claims that ATF exceeded its statutory authority and that the Rule
   violates the separation of powers were vindicated, Cargill has no standing to
   pursue these claims in federal court. 12 See Fed. Election Comm’n v. Akins, 524
   U.S. 11, 24 (1998) (explaining that, in order to have standing, plaintiffs must
   “show injury to ‘a particular right of their own, as distinguished from the
   public’s interest in the administration of the law’” (quoting Perkins v. Lukens
   Steel Co., 310 U.S. 113, 125 (1940))); California v. Texas, 141 S. Ct. 2104, 2112
   (2021) (“We do not reach these questions of the Act’s validity, however, for
   Texas and the other plaintiffs in this suit lack the standing necessary to raise
   them.”).
                                                 IV.
            For the foregoing reasons, we AFFIRM the judgment of the district
   court.

            12
                 Cargill does not argue that Congress cannot outlaw bump stocks.

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