Document ID: ./input/supremecourt_opinions/opinions/23pdf/22-976_e29g.pdf
Page Number: 11.0

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

7 

Opinion of the Court 

A 
  A semiautomatic rifle equipped with a bump stock does 
not fire 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 fired after the trigger has been released and re-
set is the result of a separate and distinct “function of the 
trigger.”  All that a bump stock does is accelerate the rate 
of fire 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 
object is “the mode of action by which it fulfils 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 fitted 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 Her-
itage Dictionary, at 1371 (“The lever pressed by the finger 
to discharge a firearm” or “[a]ny similar device used to re-
lease  or  activate  a  mechanism”);  Webster’s  New  Interna-
tional Dictionary  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 finger to 
release the cock in firing”).  The phrase “function of the trig-
ger” thus refers to the mode of action by which the trigger 
activates the firing mechanism.  For most firearms, includ-
ing  the  ones  at  issue  here,  the  trigger  is  a  curved  metal 
lever.    On  weapons  with  these  standard  trigger  mecha-
nisms, the phrase “function of the trigger” means the phys-
ical trigger movement required to shoot the firearm. 
  No  one  disputes  that  a  semiautomatic  rifle  without  a 
bump  stock  is  not  a machinegun  because  it  fires  only one 
shot per “function of the trigger.”  That is, engaging the trig-