Document ID: ./input/supremecourt_opinions/opinions/23pdf/22-976_e29g.pdf
Page Number: 27.0

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

3 

SOTOMAYOR, J., dissenting 

variety of ways.  Some would fire 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 rifle fired eight 
rounds “ ‘in a second with one pull of the trigger’ ”); see also 
Brief  for  Petitioners  22  (noting  that  a  Browning  M2  fired 
with  a  push  of  the  thumb).    Others,  such  as  the  famous 
Thompson Submachine Gun Caliber .45, or “Tommy Gun,” 
would fire continuously  only  so  long  as  the shooter main-
tained  backward  pressure  on  the  trigger;  a  shooter  could 
still  fire  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 fire the contents of the mag-
azine with  a single  prolonged pull  or  fire  a single  shot  by 
merely releasing the trigger”).  The internal mechanisms of 
automatic-fire 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 au-
tomatic  fire.    See,  e.g.,  War  Dept.,  Basic  Field  Manual: 
Thompson  Submachine  Gun,  Caliber  .45,  M1928A1,  p.  1 
(1941)  (“The  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-
inition 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  definition  still  governs  today.    See  26  U. S. C. 
§5845(b).1 
—————— 

1 Congress has twice strengthened the regulation of machineguns over 
the years without substantially updating the definition.  See Gun Con-
trol Act of 1968, 82 Stat. 1213 (expanding registration requirements and 
strengthening criminal penalties); Firearms Owners’ Protection Act, 100