Document ID: ./input/supremecourt_opinions/opinions/23pdf/22-976_e29g.pdf
Page Number: 3.0

Cite as:  602 U. S. ____ (2024) 

3 

Syllabus 

than one shot “by a single function of the trigger,” it would not do so 
“automatically.”  Section 5845(b) specifies the precise action that must 
“automatically” cause a weapon to fire “more than one shot”—a “single 
function of the trigger.”  If something more than a “single function of 
the trigger” is required to fire multiple shots, the weapon does not sat-
isfy the statutory definition.  Firing multiple shots using a semiauto-
matic rifle with a bump stock requires more than a single function of 
the trigger.  A shooter must maintain forward pressure on the rifle’s 
front grip with his nontrigger hand.  Without this ongoing manual in-
put,  a  semiautomatic  rifle  with  a  bump  stock  will  not  fire  multiple 
shots.   
   ATF counters that machineguns also require continuous manual in-
put from a shooter: The shooter must both engage the trigger and keep 
it pressed down to continue shooting.  ATF argues there is no mean-
ingful difference between holding down the trigger of a traditional ma-
chinegun and maintaining forward pressure on the front grip of a sem-
iautomatic  rifle  with  a  bump  stock.    This  argument  ignores  that 
Congress defined a machinegun by what happens “automatically” “by 
a single function of the trigger.”  Simply pressing and holding the trig-
ger down on a fully automatic rifle is not manual input in addition to 
a trigger’s function.  By contrast, pushing forward on the front grip of 
a semiautomatic rifle equipped with a bump stock is not part of func-
tioning the trigger. 
   Moreover, a semiautomatic rifle with a bump stock is indistinguish-
able from the Ithaca Model 37 shotgun, a weapon the ATF concedes 
cannot  fire  multiple  shots  “automatically.”    ATF  responds  that  a 
shooter  is  less  physically  involved  with  operating  a  bump-stock 
equipped  rifle  than operating  the  Model  37.    It explains that  once  a 
shooter pulls the rifle’s trigger a single time, the bump stock harnesses 
the  firearm’s  recoil  energy  in  a  continuous  back-and-forth  cycle  that 
allows the shooter to attain continuous firing.  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. 14–
17. 

(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 pro-
visions 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 fire continuously” at a high rate of fire, as bump stocks do.  
Brief for Petitioners 40.  So, ATF reasons, concluding that bump stocks