Garland v. Cargill

602 U.S. 406

Opinion

PRELIMINARY PRINT

Volume 602 U. S. Part 1 Pages 406–446

OFFICIAL REPORTS OF

THE SUPREME COURT June 14, 2024

REBECCA A. WOMELDORF reporter of decisions

NOTICE: This preliminary print is subject to formal revision before the bound volume is published. Users are requested to notify the Reporter of Decisions, Supreme Court of the United States, Washington, D.C. 20543, pio@supremecourt.gov, of any typographical or other formal errors. 406 OCTOBER TERM, 2023

Syllabus

GARLAND, ATTORNEY GENERAL, et al. v. CARGILL

certiorari to the united states court of appeals for the fth circuit No. 22–976. Argued February 28, 2024—Decided June 14, 2024 The National Firearms Act of 1934 defnes a “machinegun” as “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.” 26 U. S. C. § 5845(b). With a machinegun, a shooter can fre multiple times, or even continuously, by engaging the trigger only once. This capability distinguishes a machinegun from a semiautomatic frearm. With a semiautomatic frearm, the shooter can fre only one time by engaging the trigger. Using a technique called bump fring, shooters can fre semiautomatic frearms at rates approach- ing those of some machineguns. A shooter who bump fres a rife uses the frearm's recoil to help rapidly manipulate the trigger. Although bump fring does not require any additional equipment, a “bump stock” is an accessory designed to make the technique easier. A bump stock does not alter the basic mechanics of bump fring, and the trigger still must be released and reengaged to fre each additional shot. For many years, the Bureau of Alcohol, Tobacco, Firearms and Explo- sives (ATF) consistently took the position that semiautomatic rifes equipped with bump stocks were not machineguns under § 5845(b). ATF abruptly changed course when a gunman using semiautomatic ri- fes equipped with bump stocks fred hundreds of rounds into a crowd in Las Vegas, Nevada, killing 58 people and wounding over 500 more. ATF subsequently proposed a rule that would repudiate its previous guidance and amend its regulations to “clarify” that bump stocks are machineguns. 83 Fed. Reg. 13442. ATF's Rule ordered owners of bump stocks either to destroy or surrender them to ATF to avoid crimi- nal prosecution. Michael Cargill surrendered two bump stocks to ATF under protest, then fled suit to challenge the Rule under the Administrative Procedure Act. As relevant, Cargill alleged that ATF lacked statutory authority to promulgate the Rule because bump stocks are not “machinegun[s]” as defned in § 5845(b). After a bench trial, the District Court entered judgment for ATF. The Fifth Circuit initially affrmed, but reversed after rehearing en banc. A majority agreed that § 5845(b) is ambiguous as to whether a semiautomatic rife equipped with a bump stock fts Cite as: 602 U. S. 406 (2024) 407

the statutory defnition of a machinegun and resolved that ambiguity in Cargill's favor. Held: ATF exceeded its statutory authority by issuing a Rule that classi- fes a bump stock as a “machinegun” under § 5845(b). Pp. 415–429. (a) A semiautomatic rife equipped with a bump stock is not a “ma- chinegun” as defned by § 5845(b) because: (1) it cannot fre more than one shot “by a single function of the trigger” and (2) even if it could, it would not do so “automatically.” ATF therefore exceeded its statutory authority by issuing a Rule that classifes bump stocks as machine- guns. P. 415. (b) A semiautomatic rife equipped with a bump stock does not fre more than one shot “by a single function of the trigger.” The phrase “function of the trigger” refers to the mode of action by which the trig- ger activates the fring mechanism. No one disputes that a semiauto- matic rife without a bump stock is not a machinegun because a shooter must release and reset the trigger between every shot. And, any sub- sequent shot fred after the trigger has been released and reset is the result of a separate and distinct “function of the trigger.” Nothing changes when a semiautomatic rife is equipped with a bump stock. Be- tween every shot, the shooter must release pressure from the trigger and allow it to reset before reengaging the trigger for another shot. A bump stock merely reduces the amount of time that elapses between separate “functions” of the trigger. ATF argues that a shooter using a bump stock must pull the trigger only one time to initiate a bump-fring sequence of multiple shots. This initial trigger pull sets off a sequence—fre, recoil, bump, fre—that allows the weapon to continue fring without additional physical manipu- lation of the trigger by the shooter. This argument rests on the mis- taken premise that there is a difference between the shooter fexing his fnger to pull the trigger and pushing the frearm forward to bump the trigger against his stationary fnger. Moreover, ATF's position is logi- cally inconsistent because its reasoning would also mean that a semiau- tomatic rife without a bump stock is capable of fring more than one shot by a “single function of the trigger.” Yet, ATF agrees that is not the case. ATF's argument is thus at odds with itself. Pp. 415–423. (c) Even if a semiautomatic rife with a bump stock could fre more than one shot “by a single function of the trigger,” it would not do so “automatically.” Section 5845(b) specifes the precise action that must “automatically” cause a weapon to fre “more than one shot”—a “single function of the trigger.” If something more than a “single function of the trigger” is required to fre multiple shots, the weapon does not sat- isfy the statutory defnition. Firing multiple shots using a semiauto- 408 GARLAND v. CARGILL

matic rife with a bump stock requires more than a single function of the trigger. A shooter must maintain forward pressure on the rife's front grip with his nontrigger hand. Without this ongoing manual input, a semiautomatic rife with a bump stock will not fre multiple shots. ATF counters that machineguns also require continuous manual input from a shooter: The shooter must both engage the trigger and keep it pressed down to continue shooting. ATF argues there is no meaningful difference between holding down the trigger of a traditional machinegun and maintaining forward pressure on the front grip of a semiautomatic rife with a bump stock. This argument ignores that Congress defned a machinegun by what happens “automatically” “by a single function of the trigger.” Simply pressing and holding the trigger down on a fully automatic rife is not manual input in addition to a trigger's function. By contrast, pushing forward on the front grip of a semiautomatic rife equipped with a bump stock is not part of functioning the trigger. Moreover, a semiautomatic rife with a bump stock is indistinguishable from the Ithaca Model 37 shotgun, a weapon the ATF concedes cannot fre multiple shots “automatically.” ATF responds that a shooter is less physically involved with operating a bump-stock equipped rife than op- erating the Model 37. It explains that once a shooter pulls the rife's trigger a single time, the bump stock harnesses the frearm's recoil en- ergy in a continuous back-and-forth cycle that allows the shooter to attain continuous fring. But, even if one aspect of a weapon's operation could be seen as “automatic,” that would not mean the weapon “shoots . . . automatically more than one shot . . . by a single function of the trigger.” § 5845(b) (emphasis added). Pp. 424–427. (d) Abandoning the text, ATF attempts to shore up its position by relying on the presumption against ineffectiveness. That presumption weighs against interpretations of a statute that would “rende[r] the law in a great measure nugatory, and enable offenders to elude its provisions in the most easy manner.” The Emily, 9 Wheat. 381, 389. In ATF's view, Congress “restricted machineguns because they eliminate the manual movements that a shooter would otherwise need to make in order to fre continuously” at a high rate of fre, as bump stocks do. Brief for Petitioners 40. So, ATF reasons, concluding that bump stocks are lawful “simply because the [trigger] moves back and forth . . . would exalt artifce above reality and enable evasion of the federal machinegun ban.” Id., at 41–42. The presumption against ineffectiveness cannot do the work that ATF asks of it. Interpreting § 5845(b) to exclude semiautomatic rifes equipped with bump stocks comes nowhere close to making the statute useless. Pp. 427–428. 57 F. 4th 447, affrmed. Cite as: 602 U. S. 406 (2024) 409

Thomas, J., delivered the opinion of the Court, in which Roberts, C. J., and Alito, Gorsuch, Kavanaugh, and Barrett, JJ., joined. Alito, J., fled a concurring opinion, post, p. 429. Sotomayor, J., fled a dissenting opinion, in which Kagan and Jackson, JJ., joined, post, p. 429.

Principal Deputy Solicitor General Fletcher argued the cause for petitioners. With him on the briefs were Solicitor General Prelogar, Principal Deputy Assistant Attorney General Boynton, Vivek Suri, Mark B. Stern, Michael S. Raab, and Brad Hinshelwood. Jonathan F. Mitchell argued the cause for respondent. With him on the brief were Richard A. Samp, Markham S. Chenoweth, and Sheng Li.* *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 Russell C. Bogue, Assistant Attor- ney General, by Patrick J. Griffn, Chief State's Attorney of Connecticut, and by the Attorneys General for their respective States as follows: Kris- tin K. Mayes of Arizona, Rob Bonta of California, Philip J. Weiser of Colorado, 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 Joy Campbell of Massa- chusetts, Dana Nessel of Michigan, Keith Ellison of Minnesota, Aaron D. Ford of Nevada, Matthew J. Platkin of New Jersey, Raúl Torrez of New Mexico, Letitia James of New York, Joshua H. Stein of North Carolina, Ellen F. Rosenblum of Oregon, Michelle A. Henry of Pennsylvania, Peter F. Neronha of Rhode Island, Charity R. Clark of Vermont, and Robert W. Ferguson of Washington; for Chicago et al. by Myriam Zreczny Kasper, Suzanne M. Loose, Anne L. Morgan, Kathleen A. Kenealy, Sylvia O. Hinds-Radix, and Lyndsey M. Olson; for the American Medical Associa- tion et al. by Michael J. Dell; for the Constitutional Accountability Center by Elizabeth B. Wydra and Brianne J. Gorod; for the Giffords Law Center to Prevent Gun Violence et al. by Ian Simmons; and for Patrick J. Charles by L. Bradfeld Hughes. Briefs of amici curiae urging affrmance were fled for the Buckeye Institute by David C. Tryon; for the FPC Action Foundation by Joseph G. S. Greenlee, Erik S. Jaffe, and Cody J. Wisniewski; for the Firearms Pol- icy Coalition, Inc., by David H. Thompson, Peter A. Patterson, and John D. Ohlendorf; for the Firearms Regulatory Accountability Coalition et al. by Stephen J. Obermeier and Jeremy J. Broggi; for Gun Owners of 410 GARLAND v. CARGILL

Opinion of the Court

Justice Thomas delivered the opinion of the Court. Congress has long restricted access to “ `machinegun[s],' ” a category of frearms defned by the ability to “shoot, auto- matically more than one shot . . . by a single function of the trigger.” 26 U. S. C. § 5845(b); see also 18 U. S. C. § 922(o). Semiautomatic frearms, which require shooters to reengage the trigger for every shot, are not machineguns. This case asks whether a bump stock—an accessory for a semiauto- matic rife that allows the shooter to rapidly reengage the trigger (and therefore achieve a high rate of fre)—converts the rife into a “machinegun.” We hold that it does not and therefore affrm. I A Under the National Firearms Act of 1934, a “machinegun” is “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 trig- ger.” § 5845(b). The statutory defnition also includes “any part designed and intended . . . for use in converting a weapon into a machinegun.” Ibid. With a machinegun, a shooter can fre multiple times, or even continuously, by en- gaging the trigger only once. This capability distinguishes

America et al. by William J. Olson, Jeremiah L. Morgan, Robert J. Olson, and John I. Harris III; for the Manhattan Institute by Ilya Shapiro and R. Trent McCotter; for the National Association for Gun Rights, Inc., et al. by David A. Warrington, Gary M. Lawkowski, and Glenn D. Bellamy; for the National Association of Criminal Defense Lawyers by Theodore M. Cooperstein and David Oscar Markus; for the National Rife Association of America, Inc., by Michael T. Jean and Erin M. Erhardt; for the Na- tional Shooting Sports Foundation, Inc., by Paul D. Clement, Erin E. Murphy, Matthew D. Rowen, and Lawrence G. Keane; for the Second Amendment Law Center et al. by C. D. Michel and Konstadinos T. Moros; and for Sen. Cynthia Lummis et al. by David B. Kopel and George A. Mocsary. Briefs of amici curiae were fled for FAMM by David Debold, Peter Goldberger, and Mary Price; and for the Pacifc Legal Foundation by Glenn E. Roper, Steven Simpson, and Caleb Kruckenberg. Cite as: 602 U. S. 406 (2024) 411

a machinegun from a semiautomatic frearm. With a semi- automatic frearm, the shooter can fre only one time by en- gaging the trigger. The shooter must release and reengage the trigger to fre another shot. Machineguns can ordinarily achieve higher rates of fre than semiautomatic frearms be- cause the shooter does not need to release and reengage the trigger between shots. Shooters have devised techniques for fring semiautomatic frearms at rates approaching those of some machineguns. One technique is called bump fring. A shooter who bump fres a rife uses the frearm's recoil to help rapidly manipu- late the trigger. The shooter allows the recoil from one shot to push the whole frearm backward. As the rife slides back and away from the shooter's stationary trigger fnger, the trigger is released and reset for the next shot. Simulta- neously, the shooter uses his nontrigger hand to maintain forward pressure on the rife's front grip. The forward pressure counteracts the recoil and causes the frearm (and thus the trigger) to move forward and “bump” into the shoot- er's trigger fnger. This bump reengages the trigger and causes another shot to fre, and so on. Bump fring is a balancing act. The shooter must main- tain enough forward pressure to ensure that he will bump the trigger with suffcient force to engage it. But, if the shooter applies too much forward pressure, the rife will not slide back far enough to allow the trigger to reset. The right balance produces a reciprocating motion that permits the shooter to repeatedly engage and release the trigger in rapid succession. Although bump fring does not require any additional equipment, there are accessories designed to make the tech- nique easier. A “bump stock” is one such accessory.1 It re- places a semiautomatic rife's stock (the back part of the rife 1 Some bump stocks (called mechanical bump stocks) rely on an internal spring, rather than forward pressure from the shooter's nontrigger hand, to force the rife and trigger forward after recoil. These devices are not at issue in this case. 412 GARLAND v. CARGILL

that rests against the shooter's shoulder) with a plastic cas- ing that allows every other part of the rife to slide back and forth. This casing helps manage the back-and-forth motion required for bump fring. A bump stock also has a ledge to keep the shooter's trigger fnger stationary. A bump stock does not alter the basic mechanics of bump fring. As with any semiautomatic frearm, the trigger still must be released and reengaged to fre each additional shot.

B The question in this case is whether a bump stock trans- forms a semiautomatic rife into a “machinegun,” as defned by § 5845(b). For many years, the Bureau of Alcohol, To- bacco, Firearms and Explosives (ATF) took the position that semiautomatic rifes equipped with bump stocks were not machineguns under the statute. On more than 10 separate occasions over several administrations, ATF consistently concluded that rifes equipped with bump stocks cannot “au- tomatically” fre more than one shot “by a single function of the trigger.” See App. 16–68. In April 2017, for example, ATF explained that a rife equipped with a bump stock does not “operat[e] automatically” because “forward pressure must be applied with the support hand to the forward hand- guard.” Id., at 66. And, because the shooter slides the rife forward in the stock “to fre each shot, each succeeding shot fr[es] with a single trigger function.” Id., at 67. ATF abruptly reversed course in response to a mass shoot- ing in Las Vegas, Nevada. In October 2017, a gunman fred on a crowd attending an outdoor music festival in Las Vegas, killing 58 people and wounding over 500 more. The gunman equipped his weapons with bump stocks, which allowed him to fre hundreds of rounds in a matter of minutes. This tragedy created tremendous political pressure to out- law bump stocks nationwide. Within days, Members of Congress proposed bills to ban bump stocks and other de- vices “designed . . . to accelerate the rate of fre of a semiau- Cite as: 602 U. S. 406 (2024) 413

tomatic rife.” S. 1916, 115th Cong., 1st Sess., § 2 (2017); see also H. R. 3947, 115th Cong., 1st Sess. (2017); H. R. 3999, 115th Cong., 1st Sess. (2017). None of these bills became law. Similar proposals in the intervening years have also stalled. See, e.g., H. R. 396, 118th Cong., 1st Sess. (2023); S. 1909, 118th Cong., 1st Sess. (2023); H. R. 5427, 117th Cong., 1st Sess. (2021). While the frst wave of bills was pending, ATF began con- sidering whether to reinterpret § 5845(b)'s defnition of “ma- chinegun” to include bump stocks. It proposed a rule that would amend its regulations to “clarify” that bump stocks are machineguns. 83 Fed. Reg. 13442 (2018). ATF's about- face drew criticism from some observers, including those who agreed that bump stocks should be banned. Senator Dianne Feinstein, for example, warned that ATF lacked stat- utory authority to prohibit bump stocks, explaining that the proposed regulation “ `hinge[d] on a dubious analysis' ” and that the “ `gun lobby and manufacturers [would] have a feld day with [ATF's] reasoning' ” in court. Statement on Regu- lation To Ban Bump Stocks (Mar. 23, 2018). She asserted that “ `legislation is the only way to ban bump stocks.' ” Ibid. ATF issued its fnal Rule in 2018. 83 Fed. Reg. 66514. The agency's earlier regulations simply restated § 5845(b)'s statutory defnition. Ibid. The fnal Rule amended those regulations by adding the following language: “[T]he term `automatically' as it modifes `shoots, is de- signed 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 fring of multiple rounds through a single function of the trigger; and `sin- gle function of the trigger' means a single pull of the trigger and analogous motions. The term `machinegun' includes a bump-stock-type device, i.e., a device that allows a semi-automatic frearm to shoot more than one shot with a single pull of the trigger by harnessing the 414 GARLAND v. CARGILL

recoil energy of the semi-automatic frearm to which it is affxed so that the trigger resets and continues fring without additional physical manipulation of the trigger by the shooter.” Id., at 66553–66554. The fnal Rule also repudiated ATF's previous guidance that bump stocks did not qualify as “machineguns” under § 5845(b). Id., at 66530–66531. And, it ordered owners of bump stocks to destroy them or surrender them to ATF within 90 days. Id., at 66530. Bump-stock owners who failed to comply would be subject to criminal prosecution. Id., at 66525; see also 18 U. S. C. § 922(o)(1). C Michael Cargill surrendered two bump stocks to ATF under protest. He then fled suit to challenge the fnal Rule, asserting a claim under the Administrative Procedure Act. As relevant, Cargill alleged that ATF lacked statutory au- thority to promulgate the fnal Rule because bump stocks are not “machinegun[s]” as defned in § 5845(b). After a bench trial, the District Court entered judgment for ATF. The court concluded that “a bump stock fts the statutory definition of a `machinegun. ' ” Carg ill v. Bar r, 502 F. Supp. 3d 1163, 1194 (WD Tex. 2020). The Court of Appeals initially affrmed, 20 F. 4th 1004 (CA5 2021), but later reversed after rehearing en banc, 57 F. 4th 447 (CA5 2023). A majority agreed, at a minimum, that § 5845(b) is ambiguous as to whether a semiautomatic rife equipped with a bump stock fts the statutory defnition of a machinegun. And, the majority concluded that the rule of lenity required resolving that ambiguity in Cargill's favor. Id., at 469; see also id., at 450, n. An eight-judge plurality determined that the statutory defnition of “machinegun” un- ambiguously excludes such weapons. A semiautomatic rife equipped with a bump stock, the plurality reasoned, fres only one shot “each time the trigger `acts,' ” id., at 459, and so does not fre “more than one shot . . . by a single function Cite as: 602 U. S. 406 (2024) 415

of the trigger,” § 5845(b). The plurality also concluded that a bump stock does not enable a semiautomatic rife to fre more than one shot “automatically” because the shooter must “maintain manual, forward pressure on the barrel.” Id., at 463. We granted certiorari, 601 U. S. ––– (2023), to address a split among the Courts of Appeals regarding whether bump stocks meet § 5845(b)'s defnition of “machinegun.” 2 We now affrm. II Section 5845(b) defnes a “machinegun” as any weapon ca- pable of fring “automatically more than one shot . . . by a single function of the trigger.” We hold that a semiauto- matic rife equipped with a bump stock is not a “machinegun” because it cannot fre more than one shot “by a single func- tion of the trigger.” And, even if it could, it would not do so “automatically.” ATF therefore exceeded its statutory authority by issuing a Rule that classifes bump stocks as machineguns. A A semiautomatic rife equipped with a bump stock does not fre more than one shot “by a single function of the trig- ger.” With or without a bump stock, a shooter must release and reset the trigger between every shot. And, any subse- quent shot fred after the trigger has been released and reset is the result of a separate and distinct “function of the trig- ger.” All that a bump stock does is accelerate the rate of fre by causing these distinct “function[s]” of the trigger to occur in rapid succession. As always, we start with the statutory text, which refers to “a single function of the trigger.” The “function” of an

2 See, e.g., Hardin v. Bureau of Alcohol, Tobacco, Firearms and Explo- sives, 65 F. 4th 895 (CA6 2023); Guedes v. Bureau of Alcohol, Tobacco, Firearms and Explosives, 45 F. 4th 306 (CADC 2022); Aposhian v. Barr, 958 F. 3d 969 (CA10 2020). 416 GARLAND v. CARGILL

object is “the mode of action by which it fulfls its purpose.” 4 Oxford English Dictionary 602 (1933); see also American Heritage Dictionary 533 (1969) (“The natural or proper ac- tion for which a . . . mechanism . . . is ftted or employed”). And, a “trigger” is an apparatus, such as a “movable catch or lever,” that “sets some force or mechanism in action.” 11 Oxford English Dictionary, at 357; see also American Heri- tage Dictionary, at 1371 (“The lever pressed by the fnger to discharge a frearm” or “[a]ny similar device used to release or activate a mechanism”); Webster's New International Dic- tionary 2711 (2d ed. 1934) (“A piece, as a lever, connected with a catch or detent as a means of releasing it; specif., Firearms, the part of a lock moved by the fnger to release the cock in fring”). The phrase “function of the trigger” thus refers to the mode of action by which the trigger acti- vates the fring mechanism. For most frearms, including the ones at issue here, the trigger is a curved metal lever. On weapons with these standard trigger mechanisms, the phrase “function of the trigger” means the physical trigger movement required to shoot the frearm. No one disputes that a semiautomatic rife without a bump stock is not a machinegun because it fres only one shot per “function of the trigger.” That is, engaging the trigger a single time will cause the fring mechanism to discharge only one shot. To understand why, it is helpful to consider the mechanics of the fring cycle for a semiautomatic rife. Be- cause the statutory defnition is keyed to a “function of the trigger,” only the trigger assembly is relevant for our pur- poses. Although trigger assemblies for semiautomatic rifes vary, the basic mechanics are generally the same. The fol- lowing series of illustrations depicts how the trigger assem- bly on an AR–15 style semiautomatic rife works.3 In each illustration, the front of the rife (i.e., the barrel) would be pointing to the left. 3 These illustrations are found in the Brief for FPC Action Foundation as Amicus Curiae 14–15. Cite as: 602 U. S. 406 (2024) 417

We begin with an overview of the relevant components:

Figure 1. Page The triggerProof is a simplePending Publication lever that moves backward and for- ward. P. Sweeney, Gunsmithing the AR–15, p. 131 (2016). The square point at the top left edge of the trigger locks into a notch at the bottom of the hammer. P. Sweeney, Gun- smithing: Rifes 269 (1999). The hammer is a spring-loaded part that swings forward toward the barrel and strikes the fring pin, causing a shot to fre. Ibid. The disconnector is the component responsible for resetting the hammer to its original position after a shot is fred. Ibid. We turn next to how these components operate: 418 GARLAND v. CARGILL

Figure 2. When the shooter engages the trigger by moving it back- ward (as indicated by the arrow), the square point of the trigger pivots downward and out of the notch securing the hammer. Ibid. This movement releases the spring-loaded hammer, allowing it to swing forward. Ibid.

Figure 3. At the top of the hammer's rotation, it strikes the fring pin, causing the weapon to fre a single shot. See ibid. Cite as: 602 U. S. 406 (2024) 419

Figure 4. The frearm then ejects the spent cartridge from the cham- ber and loads a new one in its place. D. Long, The Complete AR–15/M16 Sourcebook 206 (2001). The mechanism that performs this task swings the hammer backward at the same time. Ibid.

Figure 5. As the hammer swings backward, it latches onto the discon- nector. Sweeney, Gunsmithing: Rifes, at 269. This latch- 420 GARLAND v. CARGILL

ing (circled above) prevents the hammer from swinging forward again after a new cartridge is loaded into the cham- ber. Ibid. The disconnector will hold the hammer in that position for as long as the shooter holds the trigger back, thus preventing the firearm from firing another shot. 4 Ibid.

Figure 6. Finally, when the shooter takes pressure off the trigger and allows it to move forward (as indicated by the arrow), the hammer slips off the disconnector just as the square point of the trigger rises into the notch on the hammer (circled above). Ibid. The trigger mechanism is thereby reset to

4 Machinegun variants of the AR–15 style rife include an additional com- ponent known as an auto sear. The auto sear catches the hammer as it swings backwards, but will release it again once a new cartridge is loaded if the trigger is being held back. P. Sweeney, 1 The Gun Digest Book of the AR–15, p. 38 (2005). An auto sear thus permits a shooter to fre multi- ple shots while engaging the trigger only once. ATF has accordingly rec- ognized that modifying a semiautomatic rife or handgun with an auto sear converts it into a machinegun. See ATF Ruling 81–4. Cite as: 602 U. S. 406 (2024) 421

the original position shown in Figure 1. A semiautomatic rife must complete this cycle for each shot fred.5 ATF does not dispute that this complete process is what constitutes a “single function of the trigger.” A shooter may fre the weapon again after the trigger has reset, but only by engaging the trigger a second time and thereby ini- tiating a new fring cycle. For each shot, the shooter must engage the trigger and then release the trigger to allow it to reset. Any additional shot fred after one cycle is the result of a separate and distinct “function of the trigger.” Nothing changes when a semiautomatic rife is equipped with a bump stock. The fring cycle remains the same. Be- tween every shot, the shooter must release pressure from the trigger and allow it to reset before reengaging the trig- ger for another shot. A bump stock merely reduces the amount of time that elapses between separate “functions” of the trigger. The bump stock makes it easier for the shooter to move the frearm back toward his shoulder and thereby release pressure from the trigger and reset it. And, it helps the shooter press the trigger against his fnger very quickly thereafter. A bump stock does not convert a semiautomatic rife into a machinegun any more than a shooter with a lightning-fast trigger fnger does. Even with a bump stock, a semiautomatic rife will fre only one shot for every “func- tion of the trigger.” So, a bump stock cannot qualify as a machinegun under § 5845(b)'s defnition. Although ATF agrees on a semiautomatic rife's mechanics, it nevertheless insists that a bump stock allows a semiauto- matic rife to fre multiple shots “by a single function of the trigger.” ATF starts by interpreting the phrase “single function of the trigger” to mean “a single pull of the trigger and analogous motions.” 83 Fed. Reg. 66553. A shooter using a bump stock, it asserts, must pull the trigger only one 5 An animated graphic that displays the relevant movements is available at https://www.supremecourt.gov/media/images/AR-15.gif. 422 GARLAND v. CARGILL

time to initiate a bump-fring sequence of multiple shots. Id., at 66554. This initial trigger pull sets off a sequence— fre, recoil, bump, fre—that allows the weapon to continue fring “without additional physical manipulation of the trig- ger by the shooter. ” Ibid. According to ATF, all the shooter must do is keep his trigger fnger stationary on the bump stock's ledge and maintain constant forward pressure on the front grip to continue fring. The dissent offers similar reasoning. See post, at 435–437 (opinion of Sotomayor, J.). This argument rests on the mistaken premise that there is a difference between a shooter fexing his fnger to pull the trigger and a shooter pushing the frearm forward to bump the trigger against his stationary fnger. ATF and the dissent seek to call the shooter's initial trigger pull a “function of the trigger” while ignoring the subsequent “bumps” of the shooter's fnger against the trigger before every additional shot. But, § 5845(b) does not defne a ma- chinegun based on what type of human input engages the trigger—whether it be a pull, bump, or something else. Nor does it defne a machinegun based on whether the shooter has assistance engaging the trigger. The statutory defni- tion instead hinges on how many shots discharge when the shooter engages the trigger. And, as we have explained, a semiautomatic rife will fre only one shot each time the shooter engages the trigger—with or without a bump stock.6 Supra, at 415–421. In any event, ATF's argument cannot succeed on its own terms. The fnal Rule defnes “function of the trigger” to

6 The dissent says that we “resis[t]” the “ordinary understanding of the term `function of the trigger' with two technical arguments.” Post, at 439. But, the arguments it refers to explain why, even assuming a semi- automatic 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.” See infra, at 424–427. Those arguments have nothing to do with our explana- tion of what a “single function of the trigger” means. Ibid. Cite as: 602 U. S. 406 (2024) 423

include not only “a single pull of the trigger” but also any “analogous motions.” 83 Fed. Reg. 66553. ATF concedes that one such analogous motion that qualifes as a single function of the trigger is “sliding the rife forward” to bump the trigger. Brief for Petitioners 22. But, if that is true, then every bump is a separate “function of the trigger,” and semiautomatic rifes equipped with bump stocks are there- fore not machineguns. ATF resists the natural implication of its reasoning, insisting that the bumping motion is a “func- tion of the trigger” only when it initiates, but not when it continues, a fring sequence. But, Congress did not write a statutory defnition of “machinegun” keyed to when a fr- ing sequence begins and ends. Section 5845(b) asks only whether a weapon fres more than one shot “by a single func- tion of the trigger.” Finally, the position that ATF and the dissent endorse is logically inconsistent. They reason that a semiautomatic rife equipped with a bump stock fres more than one shot by a single function of the trigger because a shooter “need only pull the trigger and maintain forward pressure” to “activate continuous fre.” Post, at 438–439; see also Brief for Peti- tioners 23. If that is correct, however, then the same should be true for a semiautomatic rife without a bump stock. After all, as the dissent and ATF themselves acknowledge, a shooter manually bump fring a semiautomatic rife can achieve continuous fre by holding his trigger fnger station- ary and maintaining forward pressure with his nontrigger hand. See post, at 433–434; 83 Fed. Reg. 66533. Yet, they agree that a semiautomatic rife without a bump stock “fres only one shot each time the shooter pulls the trigger.” Post, at 433; see also 83 Fed. Reg. 66534. Their argument is thus at odds with itself. We conclude that a semiautomatic rife equipped with a bump stock is not a “machinegun” because it does not fre more than one shot “by a single function of the trigger.” 424 GARLAND v. CARGILL

B A bump stock is not a “machinegun” for another reason: Even if a semiautomatic rife with a bump stock could fre more than one shot “by a single function of the trigger,” it would not do so “automatically.” Section 5845(b) asks whether a weapon “shoots . . . automatically more than one shot . . . by a single function of the trigger.” The statute thus specifes the precise action that must “automatically” cause a weapon to fre “more than one shot”—a “single func- tion of the trigger.” If something more than a “single func- tion of the trigger” is required to fre multiple shots, the weapon does not satisfy the statutory defnition. As Judge Henderson put it, the “statutory defnition of `machinegun' does not include a frearm that shoots more than one round `automatically' by a single pull of the trigger AND THEN SOME.” Guedes v. Bureau of Alcohol, Tobacco, Firearms and Explosives, 920 F. 3d 1, 44 (CADC 2019) (opinion concur- ring in part and dissenting in part). Firing multiple shots using a semiautomatic rife with a bump stock requires more than a single function of the trig- ger. A shooter must also actively maintain just the right amount of forward pressure on the rife's front grip with his nontrigger hand. See supra, at 411–412. Too much for- ward pressure and the rife will not slide back far enough to release and reset the trigger, preventing the rife from fring another shot. Too little pressure and the trigger will not bump the shooter's trigger fnger with suffcient force to fre another shot. Without this ongoing manual input, a semiau- tomatic rife with a bump stock will not fre multiple shots. Thus, fring multiple shots requires engaging the trigger one time—and then some.7 7 The dissent seemingly concedes this point, repeatedly recognizing that the shooter must both pull the trigger and maintain forward pressure on the front grip. See, e.g., post, at 435 (“[A] single pull of the trigger provides continuous fre as long as the shooter maintains forward pressure on the gun”); ibid. (“A bump-stock-equipped semiautomatic rife is a Cite as: 602 U. S. 406 (2024) 425

ATF and the dissent counter that machineguns also re- quire continuous manual input from a shooter: He must both engage the trigger and keep it pressed down to continue shooting. In their view, there is no meaningful difference between holding down the trigger of a traditional machine- gun and maintaining forward pressure on the front grip of a semiautomatic rife with a bump stock. This argument ig- nores that Congress defned a machinegun by what happens “automatically” “by a single function of the trigger.” Sim- ply pressing and 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. By contrast, pushing forward on the front grip of a semiautomatic rife equipped with a bump stock is not part of functioning the trigger. After all, pushing on the front grip will not cause the weapon to fre unless the shooter also engages the trigger with his other hand. Thus, while a fully automatic rife fres multiple rounds “automatically . . . by a single function of the trigger,” a semiautomatic rife equipped with a bump stock can achieve the same result only by a single function of the trigger and then some. Moreover, a semiautomatic rife with a bump stock is indis- tinguishable from another weapon that ATF concedes cannot fre multiple shots “automatically”: the Ithaca Model 37 shot- gun. The Model 37 allows the user to “slam fre”—that is, fre multiple shots by holding down the trigger while operat- ing the shotgun's pump action. Each pump ejects the spent cartridge and loads a new one into the chamber. If the shooter is holding down the trigger, the new cartridge will

machinegun because . . . a shooter can . . . fre continuous shots without any human input beyond maintaining forward pressure”); post, at 438 (“[A] shooter of a bump-stock-equipped AR–15 need only pull the trigger and maintain forward pressure”); post, at 441 (“After a shooter pulls the trig- ger, 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”). 426 GARLAND v. CARGILL

fre as soon as it is loaded. According to ATF, the Model 37 fres more than one shot by a single function of the trigger, but it does not do so “automatically” because the shooter must manually operate the pump action with his nontrigger hand. See 83 Fed. Reg. 66534. That logic mandates the same result here. Maintaining the proper amount of for- ward pressure on the front grip of a bump-stock equipped rife is no less additional input than is operating the pump action on the Model 37.8 ATF responds that a shooter is less physically involved with operating a bump-stock equipped rife than operating the Model 37's pump action. Once the shooter pulls the ri- fe's trigger a single time, the bump stock “harnesses the frearm's recoil energy in a continuous back-and-forth cycle that allows the shooter to attain continuous fring.” Id., at 66519. But, even if one aspect of a weapon's operation could be seen as “automatic,” that would not mean the weapon “shoots . . . automatically more than one shot . . . by a single function of the trigger.” § 5845(b) (emphasis added). After all, many weapons have some “automatic” features. For ex- ample, semiautomatic rifes eject the spent cartridge from the frearm's chamber and load a new one in its place without any input from the shooter. See supra, at 419. A semiau- tomatic rife is therefore “automatic” in the general sense that it performs some operations that would otherwise need to be completed by hand. But, as all agree, a semiautomatic rife cannot fre more than one shot “automatically . . . by a single function of the trigger” because the shooter must do

8 The dissent attempts to undermine this analogy by pointing out that a Model 37 requires manual reloading and therefore cannot qualify as a machinegun under § 5845(b). Post, at 441, n. 5. But, that is beside the point. As ATF itself agrees, the Model 37 is not a machinegun for an- other, independent reason: It cannot “automatically” fre more than one shot by a single function of the trigger. See Brief for Petitioners 38. And, as explained, the reasons why a Model 37 cannot do so apply with equal force to semiautomatic rifes equipped with bump stocks. Cite as: 602 U. S. 406 (2024) 427

more than simply engage the trigger one time. The same is true of a semiautomatic rife equipped with a bump stock. Thus, even if a semiautomatic rife could fre more than one shot by a single function of the trigger, it would not do so “automatically.” C Abandoning the text, ATF and the dissent attempt to shore up their position by relying on the presumption against ineffectiveness. That presumption weighs against interpre- tations of a statute that would “rende[r] the law in a great measure nugatory, and enable offenders to elude its provi- sions in the most easy manner.” The Emily, 9 Wheat. 381, 389 (1824). It is a modest corollary to the commonsense proposition “that Congress presumably does not enact use- less laws.” United States v. Castleman, 572 U. S. 157, 178 (2014) (Scalia, J., concurring in part and concurring in judgment). In ATF's view, Congress “restricted machineguns because they eliminate the manual movements that a shooter would otherwise need to make in order to fre continuously” at a high rate of fre, as bump stocks do. Brief for Petitioners 40. So, ATF reasons, concluding that bump stocks are law- ful “simply because the [trigger] moves back and forth . . . would exalt artifce above reality and enable evasion of the federal machinegun ban.” Id., at 41–42 (internal quotation marks omitted). The dissent endorses a similar view. See post, at 442–446. The presumption against ineffectiveness cannot do the work that ATF and the dissent ask of it. A law is not use- less merely because it draws a line more narrowly than one of its conceivable statutory purposes might suggest. Inter- preting § 5845(b) to exclude semiautomatic rifes equipped with bump stocks comes nowhere close to making it useless. Under our reading, § 5845(b) still regulates all traditional machineguns. The fact that it does not capture other weap- ons capable of a high rate of fre plainly does not render the 428 GARLAND v. CARGILL

law useless. Moreover, it is diffcult to understand how ATF can plausibly argue otherwise, given that its consistent posi- tion for almost a decade in numerous separate decisions was that § 5845(b) does not capture semiautomatic rifes equipped with bump stocks. See App. 16–68. Curiously, the dissent relegates ATF's about-face to a footnote, instead pointing to its classifcation of other devices. See post, at 441–446, and n. 6. The dissent's additional argument for applying the pre- sumption against ineffectiveness fails on its own terms. To argue that our interpretation makes § 5845(b) “far less effective,” the dissent highlights that a shooter with a bump-stock-equipped rife can achieve a rate of fre that ri- vals traditional machineguns. Post, at 445. But, the dis- sent elsewhere acknowledges that a shooter can do the same with an unmodifed semiautomatic rife using the manual bump-fring technique. See post, at 433–434. The dissent thus fails to prove that our reading makes § 5845(b) “far less effective,” much less ineffective (as is required to invoke the presumption). In any event, Congress could have linked the defnition of “machinegun” to a weapon's rate of fre, as the dissent would prefer. But, it instead enacted a statute that turns on whether a weapon can fre more than one shot “au- tomatically . . . by a single function of the trigger.” § 5845(b). And, “it is never our job to rewrite . . . statutory text under the banner of speculation about what Congress might have done.” Henson v. Santander Consumer USA Inc., 582 U. S. 79, 89 (2017).9 9 The dissent concludes by claiming that our interpretation of § 5845(b) “renders Congress's clear intent readily evadable.” Post, at 445. And, it highlights that “[e]very Member of the majority has previously em- phasized that the best way to respect congressional intent is to adhere to the ordinary understanding of the terms Congress uses.” Ibid. But, “[w]hen Congress takes the trouble to defne the terms it uses, a court must respect its defnitions as virtually conclusive. . . . This Court will not deviate from an express statutory defnition merely because it varies from the term's ordinary meaning.” Department of Agriculture Rural Devel- Cite as: 602 U. S. 406 (2024) 429

Sotomayor, J., dissenting

III For the foregoing reasons, we affrm the judgment of the Court of Appeals. It is so ordered. Justice Alito, concurring. I join the opinion of the Court because there is simply no other way to read the statutory language. There can be lit- tle doubt that the Congress that enacted 26 U. S. C. § 5845(b) would not have seen any material difference between a ma- chinegun and a semiautomatic rife equipped with a bump stock. But the statutory text is clear, and we must follow it. The horrible shooting spree in Las Vegas in 2017 did not change the statutory text or its meaning. That event dem- onstrated that a semiautomatic rife with a bump stock can have the same lethal effect as a machinegun, and it thus strengthened the case for amending § 5845(b). But an event that highlights the need to amend a law does not itself change the law's meaning. There is a simple remedy for the disparate treatment of bump stocks and machineguns. Congress can amend the law—and perhaps would have done so already if ATF had stuck with its earlier interpretation. Now that the situation is clear, Congress can act. Justice Sotomayor, with whom Justice Kagan and Justice Jackson join, dissenting. 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. his- tory. 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). 430 GARLAND v. CARGILL

commonly available, semiautomatic rifes. These simple de- vices 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 ma- chineguns 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 bipar- tisan 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 “automati- cally 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 cen- tury 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. Gang- sters like Al Capone used machineguns to rob banks, ambush Cite as: 602 U. S. 406 (2024) 431

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 main- tained 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 432 GARLAND v. CARGILL

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 def- nition 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 Pre- vent 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, al- 1 Congress 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' ”). Cite as: 602 U. S. 406 (2024) 433

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 434 GARLAND v. CARGILL

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 assem- bly 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 continu- ously. 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 ques- tion under the statute is how a person can fre it. A weapon is a “machinegun” when a shooter can (1) “by a single func- tion 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 lan- guage naturally covers devices like bump stocks, which “con- Cite as: 602 U. S. 406 (2024) 435

ver[t]” semiautomatic rifes so that a single pull of the trig- ger 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 semi- automatic 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, shift- ing focus from the internal mechanism of the gun to the perspective of the shooter, the majority holds that continu- ous 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 manu- facturers 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 trig- ger' ” as “the mode of action by which the trigger activates the fring mechanism.” Ante, at 416. Because in a bump- 436 GARLAND v. CARGILL

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 re- sets 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 trig- ger on a bump-stock-equipped semiautomatic rife sets in mo- tion. 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 “sin- gle function of the trigger” more naturally means a single initiation of the fring sequence. Regardless of what is hap- pening in the internal mechanics of a frearm, if a shooter must activate the trigger only a single time to initiate a fr- ing sequence that will shoot “automatically more than one shot,” that frearm is a “machinegun.” § 5845(b). Evidence of contemporaneous usage overwhelmingly sup- ports that interpretation. The term “ `function of the trig- ger' ” was proposed by the president of the National Rife Association (NRA) during a hearing on the National Fire- arms Act before the House. See National Firearms Act: Hearings on H. R. 9066 before the House Committee on Ways Cite as: 602 U. S. 406 (2024) 437

and Means, 73d Cong., 2d Sess., 38–40 (1934). He under- stood 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 evi- dence of legislative purpose.2 They are, along with contem- poraneous 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 as- sist . . . 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 2 Of 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). 438 GARLAND v. CARGILL

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 sup- ports 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 unre- futed 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 ac- tions 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 back- ward 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 mecha- nism 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 Cite as: 602 U. S. 406 (2024) 439

action (that is, one “single function of the trigger”) from the shooter combined with continuous pressure to activate con- tinuous fre.3 The majority resists this ordinary understanding of the term “function of the trigger” with two technical argu- ments.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 func- tion 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 trig- ger 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-stock- 3 The 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 semi- automatic rife. 4 The majority claims that these arguments explain only “why, even as- suming 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 `auto- matically.' ” 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 se- quence. Supra, at 435–439. The majority's argument for why “some- thing more than a `single function of the trigger' is required to fre multi- ple shots,” ante, at 424, is therefore relevant to both its discussion of “automatically” and my discussion of “single function of the trigger.” 440 GARLAND v. CARGILL

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 for- ward pressure cannot constitute a “single function of the trigger” because a shooter can also fre single shots by pull- ing the trigger. That logic, however, would also exclude a Tommy Gun and an M16, the paradigmatic examples of regu- lated 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 over- whelming textual and contextual evidence that “single func- tion 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 reload- ing.” § 5845(b). Put simply, the bump stock automates the process of fring more than one shot. Cite as: 602 U. S. 406 (2024) 441

Before automatic weapons, a person who wanted to fre multiple shots from a frearm had to do two things after pull- ing 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 back- ward 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 au- tomation 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 5 The majority attempts to analogize a bump stock to the Model 37 shot- gun, 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 cham- ber.” Ante, at 425–426. 442 GARLAND v. CARGILL

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-stock- equipped 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 ma- chinegun that requires a user to hold down a button. Mak- ers of automatic weapons may require continuous human input for safety purposes; an accidental trigger pull that acti- vates rapid fre is less harmful if it does not require affrma- tive 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 “eva- sion,” “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. Cite as: 602 U. S. 406 (2024) 443

Before machineguns, a shooter could fre a gun only as fast as his fnger could pull the trigger. Congress sought to re- strict the civilian use of machineguns because they elimi- nated the need for a person rapidly to pull the trigger him- self 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 trans- form semiautomatic rifes into weapons capable of rapid fre with a single function of the trigger. Recognizing the cre- ativity 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, with- out manual reloading, by a single function of the trigger.” § 5845(b). Not “more than four, fve, or six shots,” not “sin- gle pull” or “single push” of the trigger. Following that defnition, the Bureau of Alcohol, Tobacco, Firearms and Ex- plosives (ATF) has reasonably classifed many transforma- tive 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

6 The 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 de- vices 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) (uphold- ing classifcation of fshing reel attached to a rife trigger that, upon activa- tion, repeatedly operated the curved lever of the rife). 444 GARLAND v. CARGILL

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 pres- sure 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 de- vices 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 acti- vate 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 ineffec- tiveness, 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

7 Respondent does not today challenge ATF's classifcation of these de- vices 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 me- chanical actions to fre continuously, even when a shooter initiates that fre with a single human action. Cite as: 602 U. S. 406 (2024) 445

“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 ma- jority creates a defnition of the statute that bans only “tradi- tional” machineguns, even though its defnition renders Con- gress'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 construc- tion must begin with the language employed by Congress and the assumption that the ordinary meaning of that lan- guage 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, contempo- rary, common meaning, absent an indication Congress in- tended 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 inter- pret 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 de- parting from “all indications of ordinary meaning” will “cre- ate regulatory uncertainty for the Federal Government . . . and regulated parties”); Bartenwerfer v. Buckley, 598 U. S. 446 GARLAND v. CARGILL

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 ma- chineguns from gunmen like the Las Vegas shooter. I re- spectfully dissent. 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