On October 1, 2017, a shooter opened fre from a hotel room overlooking an outdoor concert in Las Vegas, Nevada, in what would become the deadliest mass shooting in U. S. history. Within a matter of minutes, using several hundred rounds of ammunition, the shooter killed 58 people and wounded over 500. He did so by affxing bump stocks to opment Rural Housing Service v. Kirtz, 601 U. S. 42, 59 (2024) (internal quotation marks and alteration omitted) (unanimous opinion). Page Proof Pending Publication commonly available, semiautomatic rifes. These simple devices harness a rife's recoil energy to slide the rife back and forth and repeatedly “bump” the shooter's stationary trigger fnger, creating rapid fre. All the shooter had to do was pull the trigger and press the gun forward. The bump stock did the rest.
Congress has sharply restricted civilian ownership of machineguns since 1934. Federal law defnes a “machinegun” as a weapon that can shoot “automatically more than one shot, without manual reloading, by a single function of the trigger.” 26 U. S. C. § 5845(b). Shortly after the Las Vegas massacre, the Trump administration, with widespread bipartisan support, banned bump stocks as machineguns under the statute.
Today, the Court puts bump stocks back in civilian hands. To do so, it casts aside Congress's defnition of “machinegun” and seizes upon one that is inconsistent with the ordinary meaning of the statutory text and unsupported by context or purpose. When I see a bird that walks like a duck, swims like a duck, and quacks like a duck, I call that bird a duck. A bump-stock-equipped semiautomatic rife fres “automatically more than one shot, without manual reloading, by a single function of the trigger.” § 5845(b). Because I, like Congress, call that a machinegun, I respectfully dissent.
I
A
Machineguns were originally developed in the 19th century as weapons of war. See J. Ellis, The Social History of the Machine Gun 21–45 (1986) (Ellis). Smaller and lighter submachine guns were not commercially available until the 1920s. See Brief for Patrick J. Charles as Amicus Curiae 5 (Charles Brief). Although these weapons were originally marketed to law enforcement, they inevitably made it into the hands of gangsters. See id., at 8–9; Ellis 149–165. Gangsters like Al Capone used machineguns to rob banks, ambush Page Proof Pending Publication the police, and murder rivals. See Ellis 153–154, 157–158. Newspaper headlines across the country fashed “ `Gangsters Use Machine Guns,' ” “ `Machine Gun Used in Bank Hold- Up,' ” and “ `Machine Gun Thugs Kill Postal Employee.' ” Charles Brief 9.
Congress responded in 1934 by sharply restricting civilian ownership of machineguns. See National Firearms Act of 1934, §§ 3–6, 48 Stat. 1236, 1237–1238. The Senate Report explaining the 1934 Act emphasized that the “gangster as a law violator must be deprived of his most dangerous weapon, the machine gun.” S. Rep. No. 1444, 73d Cong., 2d Sess., 1–2. “[W]hile there is justifcation for permitting the citizen to keep a pistol or revolver for his own protection . . . , there is no reason why anyone except a law offcer should have a machine gun.” Id., at 2.
These early machineguns allowed a shooter to fre in a variety of ways. Some would fre continuously with a single pull of the trigger or push of a button. See Charles Brief 7, and n. 12 (noting that a Browning M1918 rife fred eight rounds “ `in a second with one pull of the trigger' ”); see also Brief for Petitioners 22 (noting that a Browning M2 fred with a push of the thumb). Others, such as the famous Thompson Submachine Gun Caliber .45, or “Tommy Gun,” would fre continuously only so long as the shooter maintained backward pressure on the trigger; a shooter could still fre single shots by pulling and releasing the trigger each time. See Test of Thompson Submachine Gun, 69 Army and Navy Register 355 (Apr. 9, 1921) (noting that the shooter of a Tommy Gun “can fre the contents of the magazine with a single prolonged pull or fre a single shot by merely releasing the trigger”). The internal mechanisms of automatic-fre weapons also varied enormously, with many (such as the Tommy Gun) relying principally on the recoil energy produced by each bullet's discharge to effectuate automatic fre. See, e.g., War Dept., Basic Field Manual: Thompson Submachine Gun, Caliber .45, M1928A1, p. 1 (1941) (“The Page Proof Pending Publication Thompson submachine gun . . . is an air-cooled, recoil- operated, magazine-fed weapon”); W. Smith, Small Arms of the World: The Basic Manual of Military Small Arms 165 (1955) (describing Tommy guns as “recoil operated weapons on the elementary blowback principle”).
To account for these differences, Congress adopted a defnition of “machinegun” that captured “any weapon which shoots, or is designed to shoot, automatically . . . more than one shot, without manual reloading, by a single function of the trigger.” National Firearms Act, 48 Stat. 1236. That essential defnition still governs today. See 26 U. S. C. § 5845(b).1
B
The archetypal modern “machinegun” is the military's standard-issue M16 assault rife. With an M16 in automatic mode, the shooter pulls the trigger once to achieve a fre rate of 700 to 950 rounds per minute. See Dept. of Defense, Defense Logistics Agency, Small Arms, https://www.dla.mil/ Disposition-Services/Offers/Law-Enforcement/Weapons.
An internal mechanism automates the M16's continuous fre, so that all the shooter has to do is keep backward pressure on the trigger. See Brief for Giffords Law Center to Prevent Gun Violence et al. as Amici Curiae 9–11 (Giffords Brief) (discussing internal fring mechanism of M16). If the shooter stops putting pressure on the trigger, the gun stops fring.
Semiautomatic weapons are not “machineguns” under the statute. Take, for instance, an AR–15-style semiautomatic rife. To rapidly fre an AR–15, a shooter must rapidly pull the trigger himself. It is “semi” automatic because, al1Congress has twice strengthened the regulation of machineguns over the years without substantially updating the defnition. See Gun Control Act of 1968, 82 Stat. 1213 (expanding registration requirements and strengthening criminal penalties); Firearms Owners' Protection Act, 100 Stat. 452–453 (making it a federal crime “ `to transfer or possess a machinegun' ”).
Page Proof Pending Publication though the rife automatically loads a new cartridge into the chamber after it is fred, it fres only one shot each time the shooter pulls the trigger. See 18 U. S. C. § 921(a)(29) (2018 ed., Supp. IV).
To fre an M16 or AR–15 rife, a person typically holds the “grip” next to the trigger with his fring hand. He stabilizes the weapon with his other hand on its barrel or “front grip.” He then raises the weapon so that the butt, or “stock,” of the gun rests against his shoulder, lines up the sights to look down the gun, and squeezes the trigger. See Dept. of the Army, Field Manual 23–9, Rifle Marksmanship M16A1, M16A2/3, M16A4, and M4 Carbine, Ch. 4, Section III, p. 4– 22 (Sept. 13, 2006) (M16 Field Manual). A regular person with an AR–15 can achieve a fre rate of around 60 rounds per minute, with one pull of the trigger per second. Tr. of Oral Arg. 39. A professional sport shooter can use the AR– 15 to fre at a rate of up to 180 rounds per minute, pulling the trigger three times per second. Giffords Brief 14.
A shooter can also manually “bump” an AR–15 to increase the rate of fre by using a belt loop or rubber band to hold his trigger fnger in place and harness the recoil from the frst shot to fre the rife continuously. See 83 Fed. Reg.
66532–66533 (2018). To use a belt loop, he must hold the rife low against his hip, put his fnger in the trigger guard, and then loop his fnger through a belt loop on his pants to lock the fnger in place. See id., at 66533. With his other hand, he then pushes the rife forward until his stationary fnger engages the trigger to fre the frst shot. See ibid. The recoil from that shot pushes the rife violently backward. See ibid. If the shooter keeps pressing the rife forward against the fnger in his belt loop, the repeated backward jump of the recoil combined with his forward pressure allows the rife to fre continuously. See ibid. A shooter using this method, however, cannot shoot very precisely. He has neither the advantage of the sights to line up his shot, nor his shoulder to stabilize the recoil. A shooter can also use Page Proof Pending Publication Page Proof Pending Publication a rubber band or zip tie to tie a fnger close to the trigger. See id., at 66532. If the shooter is strong and skilled enough physically to control the distance and direction of the rife's signifcant recoil, the rife will fre continuously.
A bump stock automates and stabilizes the bump fring process. It replaces a rife's standard stock, which is the part held against the shoulder. See id., at 66516. A bump stock, unlike a standard stock, allows the rife's upper assembly to slide back and forth in the stock. See ibid. It also typically includes a fnger rest on which the shooter can place his fnger while shooting, and a “receiver module” that guides and regulates the weapon's recoil. Ibid. To fre a semiautomatic rife equipped with a bump stock, the shooter either pulls the trigger, see ibid., or slides the gun forward in the bump stock, which presses the trigger into his trigger fnger, Cargill v. Barr, 502 F. Supp. 3d 1163, 1175 (WD Tex. 2020). As long as the shooter keeps his trigger fnger on the fnger rest and maintains constant forward pressure on the rife's barrel or front grip, the weapon will fre continuously. See 83 Fed. Reg. 66516. A rife equipped with a bump stock can fre at a rate between 400 and 800 rounds per minute. Tr. of Oral Arg. 40.
II
A machinegun does not fre itself. The important question under the statute is how a person can fre it. A weapon is a “machinegun” when a shooter can (1) “by a single function of the trigger,” (2) shoot “automatically more than one shot, without manually reloading.” 26 U. S. C. § 5845(b). The plain language of that defnition refers most obviously to a rife like an M16, where a single pull of the trigger provides continuous fre as long as the shooter maintains backward pressure on the trigger. The defnition of “machinegun” also includes “any part designed and intended . . . for use in converting a weapon into a machinegun.” Ibid. That language naturally covers devices like bump stocks, which “conver[t]” semiautomatic rifes so that a single pull of the trigger provides continuous fre as long as the shooter maintains forward pressure on the gun.
This is not a hard case. All of the textual evidence points to the same interpretation. A bump-stock-equipped semiautomatic rife is a machinegun because (1) with a single pull of the trigger, a shooter can (2) fre continuous shots without any human input beyond maintaining forward pressure.
The majority looks to the internal mechanism that initiates fre, rather than the human act of the shooter's initial pull, to hold that a “single function of the trigger” means a reset of the trigger mechanism. Its interpretation requires six diagrams and an animation to decipher the meaning of the statutory text. See ante, at 417–421, and n. 5. Then, shifting focus from the internal mechanism of the gun to the perspective of the shooter, the majority holds that continuous forward pressure is too much human input for bump-stock-enabled continuous fre to be “automatic.” See ante, at 424–427.
The majority's reading fies in the face of this Court's standard tools of statutory interpretation. By casting aside the statute's ordinary meaning both at the time of its enactment and today, the majority eviscerates Congress's regulation of machineguns and enables gun users and manufacturers to circumvent federal law.
A
Start with the phrase “single function of the trigger.” All the tools of statutory interpretation, including dictionary defnitions, evidence of contemporaneous usage, and this Court's prior interpretation, point to that phrase meaning the initiation of the fring sequence by an act of the shooter, whether via a pull, push, or switch of the fring mechanism. The majority nevertheless interprets “ `function of the trigger' ” as “the mode of action by which the trigger activates the fring mechanism.” Ante, at 416. Because in a bumpPage Proof Pending Publication stock-equipped semiautomatic rife, the trigger's internal mechanism must reset each time a weapon fres, the majority reads each reset as a new “function.” That reading fxates on a frearm's internal mechanics while ignoring the human act on the trigger referenced by the statute.
Consider the relevant dictionary defnitions. In 1934, when Congress passed the National Firearms Act, “function” meant “the mode of action by which [something] fulfls its purpose.” 4 Oxford English Dictionary 602 (1933). A “trigger” meant the “movable catch or lever” that “sets some force or mechanism in action.” 11 id., at 357. The majority agrees with those defnitions. Ante, at 415–416.
It errs, however, by maintaining a myopic focus on a trig- ger's mechanics rather than on how a shooter uses a trigger to initiate fre. Ante, at 416.
Nothing about those defnitions suggests that “function of the trigger” means the mechanism by which the trigger resets mechanically to fre a second shot. See ante, at 416– 421 (explaining the interior mechanics of an AR–15 trigger mechanism), as opposed to the process that a pull of the trigger on a bump-stock-equipped semiautomatic rife sets in motion. The most important “function” of a “trigger” is what it enables a shooter to do; what “force or mechanism” it sets “in action.” 11 Oxford English Dictionary, at 357. A “single function of the trigger” more naturally means a single initiation of the fring sequence. Regardless of what is happening in the internal mechanics of a frearm, if a shooter must activate the trigger only a single time to initiate a fring sequence that will shoot “automatically more than one shot,” that frearm is a “machinegun.” § 5845(b).
Evidence of contemporaneous usage overwhelmingly supports that interpretation. The term “ `function of the trigger' ” was proposed by the president of the National Rife Association (NRA) during a hearing on the National Firearms Act before the House. See National Firearms Act: Hearings on H. R. 9066 before the House Committee on Ways Page Proof Pending Publication and Means, 73d Cong., 2d Sess., 38–40 (1934). He understood the “distinguishing feature of a machine gun [to be] that by a single pull of the trigger the gun continues to fre.” Id., at 40. He emphasized that a frearm “which is capable of fring more than one shot by a single pull of the trigger, a single function of the trigger, is properly regarded . . . as a machine gun.” Ibid. Distinguishing a machinegun from a pistol, the NRA president emphasized that for a pistol “[y]ou must release the trigger and pull it again for the second shot to be fred.” Id., at 41. He did not say “the hammer slips off the disconnector just as the square point of the trigger rises into the notch on the hammer . . . thereby reset[ting the trigger mechanism] to the original position.” Ante, at 420–421. He instead emphasized the action of the shooter, who must repeatedly activate the trigger for each shot.
Predictably, the House and Senate Reports refect the same understanding of the phrase. See H. R. Rep. No. 1780, 73d Cong., 2d Sess., 2 (1934) (reporting that the statute “contains the usual defnition of machine gun as a weapon designed to shoot more than one shot without reloading and by a single pull of the trigger”); S. Rep. No. 1444, 73d Cong., 2d Sess., 2 (1934) (same).
The majority cannot disregard these statements as evidence of legislative purpose.2 They are, along with contemporaneous dictionary defnitions, some of the best evidence of contemporaneous understanding. Cf. McDonald v. Chicago, 561 U. S. 742, 828 (2010) (Thomas, J., concurring in part and concurring in judgment) (“Statements by legislators can assist . . . to the extent they demonstrate the manner in which the public used or understood a particular word or phrase”). Indeed, at oral argument, when asked what evidence there was “that as of 1934, the ordinary understanding of the 2Of course, “authoritative legislative history can be useful, even when the meaning can be discerned from the statute's language, to reinforce or to confrm a court's sense of the text.” R. Katzmann, Judging Statutes 35 (2014).
Page Proof Pending Publication Page Proof Pending Publication phrase `function of the trigger' referred to the mechanics of the gun rather than . . . the shooter's motion,” respondent's lawyer could not point to a single piece of evidence that supports the majority's reading. Tr. of Oral Arg. 98; see id., at 98–101. He even agreed that Congress used the word “function” to ensure that the statute covered a wide variety of trigger mechanisms, including both push and pull triggers. Id., at 101–102. In short, the majority disregards the unrefuted evidence of the text's ordinary and contemporaneous meaning, substituting instead its own understanding of the internal mechanics of an AR–15 without looking at the actions of the shooter.
This Court itself has also previously read the defnition of “machinegun” in this exact statute to refer to the action of the shooter rather than the fring mechanism. In Staples v. United States, 511 U. S. 600 (1994), the Court noted that “a weapon that fres repeatedly with a single pull of the trig ger” is a machinegun, as opposed to “a weapon that fres only one shot with each pull of the trigger,” which is (at most) a semiautomatic frearm. Id., at 602, n. 1 (emphasis added). A “pull” of the trigger necessarily requires human input. When a shooter initiates the firing sequence on a bump-stock-equipped semiautomatic rife, he does so with “a single function of the trigger” under that term's ordinary meaning. Just as the shooter of an M16 need only pull the trigger and maintain backward pressure (on the trigger), a shooter of a bump-stock-equipped AR–15 need only pull the trigger and maintain forward pressure (on the gun). Both shooters pull the trigger only once to fre multiple shots. The only difference is that for an M16, the shooter's backward pressure makes the rife fre continuously because of an internal mechanism: The curved lever of the trigger does not move. In a bump-stock-equipped AR–15, the mechanism for continuous fre is external: The shooter's forward pressure moves the curved lever back and forth against his stationary trigger fnger. Both rifes require only one initial Page Proof Pending Publication action (that is, one “single function of the trigger”) from the shooter combined with continuous pressure to activate continuous fre.3 The majority resists this ordinary understanding of the term “function of the trigger” with two technical arguments.4 First, it attempts to contrast the action required to fre an M16 from that required to fre a bump-stock-equipped AR–15. The majority argues that “holding the trigger down on a fully automatic rife is not manual input in addition to a trigger's function—it is what causes the trigger to function in the frst place” whereas “pushing on the front grip [of a bump-stock equipped semiautomatic rife] will not cause the weapon to fre unless the shooter also engages the trigger with his other hand.” Ante, at 425. The shooter of a bump-stock-equipped AR–15, however, need not “pull” the trigger to fre. Instead, he need only place a fnger on the fnger rest and push forward on the front grip or barrel with his other hand. Instead of pulling the trigger, the forward motion pushes the bump stock into his fnger.
Second, the majority tries to cabin “single function of the trigger” to a single mechanism for activating continuous fre. See ante, at 424–425. A shooter can fre a bump-stock3The majority thinks that this logic should apply just as well to manual bump fring. Ante, at 423. As described supra, at 433–434, and infra, at 441–442, however, bump fring requires much more from the shooter than the simple forward pressure required to fre a bump-stock-equipped semiautomatic rife.
4The majority claims that these arguments explain only “why, even assuming a semiautomatic rife equipped with a bump stock could fre more than one shot by a single function of the trigger, it could not do so `automatically.' ” Ante, at 422, n. 6. That is correct, as far as the majority's reasoning goes. The majority defnes “ `single function of the trigger' ” as a reset of a rife's internal trigger mechanism. Ante, at 421. A more accurate defnition is the human action required to initiate the fring sequence. Supra, at 435–439. The majority's argument for why “something more than a `single function of the trigger' is required to fre multiple shots,” ante, at 424, is therefore relevant to both its discussion of “automatically” and my discussion of “single function of the trigger.” equipped semiautomatic rife in two ways. First, he can choose to fre single shots via distinct pulls of the trigger without exerting any additional pressure. Second, he can fre continuously via maintaining constant forward pressure on the barrel or front grip. The majority holds that the forward pressure cannot constitute a “single function of the trigger” because a shooter can also fre single shots by pulling the trigger. That logic, however, would also exclude a Tommy Gun and an M16, the paradigmatic examples of regulated machineguns in 1934 and today. Both weapons can fre either automatically or semiautomatically. A shooter using a Tommy Gun in automatic mode could choose to fre single shots with distinct pulls of the trigger, or continuous shots by maintaining constant backward pressure on the trigger. See supra, at 431. An M16 user can toggle the weapon from semiautomatic mode, which allows only one shot per pull of the trigger, to automatic mode, which enables continuous fre. See M16 Field Manual, Ch. 4, Section III, p. 4–8. In 1934 as now, there is no commonsense difference between a frearm where a shooter must hold down a trigger or fip a switch to initiate rapid fre and one where a shooter must push on the front grip or barrel to do the same.
The majority's logic simply does not overcome the overwhelming textual and contextual evidence that “single function of the trigger” means a single action by the shooter to initiate a fring sequence, including pulling a trigger and pushing forward on a bump-stock-equipped semiautomatic rife.
B
Next, consider what makes a machinegun “automatic.” A bump-stock-equipped semiautomatic rife is a “machinegun” because with a “single function of the trigger” it “shoot[s], automatically more than one shot, without manual reloading.” § 5845(b). Put simply, the bump stock automates the process of fring more than one shot.
Page Proof Pending Publication Page Proof Pending Publication Before automatic weapons, a person who wanted to fre multiple shots from a frearm had to do two things after pulling the trigger the frst time: (1) he had to reload the gun; and (2) he had to pull the trigger again. A semiautomatic weapon like an AR–15 already automates the frst process.
The bump stock automates the second.5 In a fully automatic rife like an M16, that automation is internal. After a shooter pulls the trigger, if he maintains continuous backward pressure on the trigger, the curved lever itself will not move. Instead, an internal mechanism allows continuous fre. On a bump-stock-equipped semiautomatic rife, the automation is external. After a shooter pulls the trigger, if he maintains continuous forward pressure on the gun, the bump stock harnesses the recoil to move the curved lever back and forth against his fnger. That external automated motion creates continuous fre.
When a shooter “bump” fres a semiautomatic weapon without a bump stock, he must control several things using his own strength and skill: (1) the backward recoil of each shot, including both the direction in which the rife moves and how far it moves when recoiling; (2) the trigger fnger, by maintaining a stationary position with a loose enough hold on the trigger that the rapidly moving gun will hit his fnger each time; and (3) the forward motion of the rife after it recoils backward. A bump stock automates those processes. The replacement stock controls the direction and distance of the recoil, and the fnger rest obviates the need to maintain 5The majority attempts to analogize a bump stock to the Model 37 shotgun, which allows the user to “fre multiple shots by holding down the trigger while operating the shotgun's pump action.” Ante, at 425. The Model 37 automates the second process (i.e., pulling the trigger for each shot), as long as the shooter maintains pressure on the trigger. Unlike a semiautomatic rife, however, the Model 37 does not automate the frst, as the shooter “must manually operate the pump action with his nontrigger hand” to “ejec[t] the spent cartridge and loa[d] a new one into the chamber.” Ante, at 425–426.
a stationary fnger position. All a shooter must do is rest his fnger and press forward on the front grip or barrel for the rife to fre continuously.
The majority nevertheless concludes that a bump-stockequipped semiautomatic rife requires too much human input to fire “ `automatically' ” because it requires the “proper amount of forward pressure on the front grip” to maintain continuous fre. Ante, at 426. “Automati[c],” however, does not mean zero human input. An M16 requires the shooter to exert the “proper amount of [backward] pressure on the” trigger to maintain continuous fre. Ibid. So, too, a machinegun that requires a user to hold down a button. Makers of automatic weapons may require continuous human input for safety purposes; an accidental trigger pull that activates rapid fre is less harmful if it does not require affrmative human action to stop. Requiring continuous pressure for continuous fre, however, does not prevent a frearm from “shoot[ing], automatically more than one shot.” § 5845(b).
C
This Court has repeatedly avoided interpretations of a statute that would facilitate its ready “evasion” or “enable offenders to elude its provisions in the most easy manner.” The Emily, 9 Wheat. 381, 389–390 (1824); see also Abramski v. United States, 573 U. S. 169, 181–182, 185 (2014) (declining to read a gun statute in a way that would permit ready “evasion,” “defeat the point” of the law, or “easily bypass the scheme”). Justice Scalia called this interpretive principle the “presumption against ineffectiveness.” A. Scalia & B. Garner, Reading Law: The Interpretation of Legal Texts 63 (2012). The majority arrogates Congress's policymaking role to itself by allowing bump-stock users to circumvent Congress's ban on weapons that shoot rapidly via a single action of the shooter.
“The presumption against ineffectiveness ensures that a text's manifest purpose is furthered, not hindered.” Ibid. Page Proof Pending Publication Before machineguns, a shooter could fre a gun only as fast as his fnger could pull the trigger. Congress sought to restrict the civilian use of machineguns because they eliminated the need for a person rapidly to pull the trigger himself to fre continuously. A bump stock serves that function. Even a skilled sport shooter can fre an AR–15 at a rate of only 180 rounds per minute by rapidly pulling the trigger. Anyone shooting a bump-stock-equipped AR–15 can fre at a rate between 400 and 800 rounds per minute with a single pull of the trigger.
Moreover, bump stocks are not the only devices that transform semiautomatic rifes into weapons capable of rapid fre with a single function of the trigger. Recognizing the creativity of gun owners and manufacturers, Congress wrote a statute “loaded with anticircumvention devices.” Tr. of Oral Arg. 68. The defnition of “machinegun” captures “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.” § 5845(b). Not “more than four, fve, or six shots,” not “single pull” or “single push” of the trigger. Following that defnition, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) has reasonably classifed many transformative devices other than bump stocks as “machinegun[s].” 6 For instance, ATF has long classifed “forced reset triggers” as machineguns. See Brief for Petitioners 28. A forced 6The majority emphasizes that ATF previously took the position that certain bump-stock devices were not “machinegun[s]” under the statute. See ante, at 412, 428. ATF, however, has repeatedly classifed other devices that modify semiautomatic rifes by allowing a single activation of the shooter to automate repeat fre as machineguns. See, e.g., 83 Fed. Reg. 66518, n. 4 (referencing ATF classifcations of trigger reset devices); Akins v. United States, 312 Fed. Appx. 197, 200–201 (CA11 2009) (per cu riam) (upholding classifcation of Akins Accelerator, a spring-operated bump stock); United States v. Camp, 343 F. 3d 743, 745 (CA5 2003) (upholding classifcation of fshing reel attached to a rife trigger that, upon activation, repeatedly operated the curved lever of the rife).
Page Proof Pending Publication Page Proof Pending Publication reset trigger includes a device that forces the trigger back downward after the shooter's initial pull, repeatedly pushing the curved lever against the shooter's stationary trigger finger.
See ibid.
To a shooter, a semiautomatic rifle equipped with a forced reset trigger feels much like an M16. He must pull the trigger only once and then maintain pressure to achieve continuous fre. See ibid.
Gun owners themselves also have built motorized devices that will repeatedly pull a semiautomatic frearm's curved lever to enable continuous fre. ATF has classifed such devices as “machinegun[s]” since 1982. See Record 1077. In 2003, the Fifth Circuit held that such a contraption qualifed as a “machinegun” under the statute. See United States v. Camp, 343 F. 3d 743, 745. An owner of a semiautomatic rife had placed a fshing reel inside the weapon's trigger guard. Id., at 744. When he pulled a switch behind the original trigger, the switch supplied power to a motor connected to the fshing reel. Ibid. The motor caused the reel to rotate, and that rotation manipulated the curved lever, causing it to fre in rapid succession. Ibid. ATF in 2017 also classifed as a “machinegun” a wearable glove that a shooter could activate to initiate a mechanized piston moving back and forth, repeatedly pulling and releasing a semiautomatic rife's curved lever. See Record 1074–1076.7 The majority tosses aside the presumption against ineffectiveness, claiming that its interpretation only “draws a line more narrowly than one of [Congress's] conceivable statutory purposes might suggest” because the statute still regulates 7Respondent does not today challenge ATF's classifcation of these devices as “machinegun[s].” His lawyer noted at oral argument, however, that “forced reset triggers” would be part of a category of “harder cases” where “there may be a question as to what exactly the trigger is and then how does that trigger function.” Tr. of Oral Arg. 82. That ambiguity stems from the majority's loophole for weapons that require multiple mechanical actions to fre continuously, even when a shooter initiates that fre with a single human action.
“all traditional machineguns” like M16s. Ante, at 427.
Congress's ban on M16s, however, is far less effective if a shooter can instead purchase a bump stock or construct a device that enables his AR–15 to fre at the same rate. Even bump-stock manufacturers recognize that they are exploiting a loophole, with one bragging on its website “Bumpfre Stocks are the closest you can get to full auto and still be legal.” Mid- south Shooters, BUMPFIRE SYSTEMS, https://www.
midsouthshooterssupply.com/b/bumpfre-systems. The majority creates a defnition of the statute that bans only “traditional” machineguns, even though its defnition renders Congress's clear intent readily evadable.
Every Member of the majority has previously emphasized that the best way to respect congressional intent is to adhere to the ordinary understanding of the terms Congress uses. See, e.g., Jam v. International Finance Corp., 586 U. S. 199, 209 (2019) (Roberts, C. J., for the Court) (“ ‘[T]he legislative purpose is expressed by the ordinary meaning of the words used' ”); Gross v. FBL Financial Services, Inc., 557 U. S. 167, 175 (2009) (Thomas, J., for the Court) (“ `Statutory construction must begin with the language employed by Congress and the assumption that the ordinary meaning of that language accurately expresses the legislative purpose' ”); Wall v. Kholi, 562 U. S. 545, 551 (2011) (Alito, J., for the Court) (“ `We give the words of a statute their ordinary, contemporary, common meaning, absent an indication Congress intended them to bear some different import' ”); BP p.l.c. v. Mayor and City Council of Baltimore, 593 U. S. 230, 237 (2021) (Gorsuch, J., for the Court) (“When called on to interpret a statute, this Court generally seeks to discern and apply the ordinary meaning of its terms at the time of their adoption”); Sackett v. EPA, 598 U. S. 651, 723, 727 (2023) (Kavanaugh, J., concurring in judgment) (reasoning that departing from “all indications of ordinary meaning” will “create regulatory uncertainty for the Federal Government . . . and regulated parties”); Bartenwerfer v. Buckley, 598 U. S. Page Proof Pending Publication 69, 77, 83 (2023) (Barrett, J., for the Court) (declining to “artifcially narrow ordinary meaning” to “second-guess [Congress's] judgment”). Today, the majority forgets that principle and substitutes its own view of what constitutes a “machinegun” for Congress's.
* * * Congress's defnition of “machinegun” encompasses bump stocks just as naturally as M16s. Just like a person can shoot “automatically more than one shot” with an M16 through a “single function of the trigger” if he maintains continuous backward pressure on the trigger, he can do the same with a bump-stock-equipped semiautomatic rife if he maintains forward pressure on the gun. § 5845(b). Today's decision to reject that ordinary understanding will have deadly consequences. The majority's artificially narrow defnition hamstrings the Government's efforts to keep machineguns from gunmen like the Las Vegas shooter. I respectfully dissent.
Page Proof Pending Publication Page Proof Pending Publication 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. 407, line 12 from bottom: “trigger” is replaced with “fnger” p. 423, line 3 from bottom: “a” is inserted after “that” p. 432, line 2 from bottom: “assault” is deleted