Document ID: ./input/supremecourt_opinions/opinions/21pdf/20-843_7j80.pdf
Page Number: 25

Cite as:  597 U. S. ____ (2022) 

19 

Opinion of the Court 

as those that preoccupied the Founders in 1791 or the Re-
construction generation in 1868.  Fortunately, the Found-
ers  created  a  Constitution—and  a  Second  Amendment— 
“intended to endure for ages to come, and consequently, to 
be adapted to the various crises of human affairs.”  McCul-
loch v. Maryland, 4 Wheat. 316, 415 (1819) (emphasis de-
leted).  Although its meaning is fixed according to the un-
derstandings of those who ratified it, the Constitution can,
and must, apply to circumstances beyond those the Found-
ers  specifically  anticipated.    See,  e.g.,  United  States  v. 
Jones, 565 U. S. 400, 404–405 (2012) (holding that installa-
tion  of  a  tracking  device  was  “a  physical  intrusion  [that] 
would have been considered a ‘search’ within the meaning 
of the Fourth Amendment when it was adopted”). 

We have already recognized in Heller at least one way in
which the Second Amendment’s historically fixed meaning 
applies to new circumstances: Its reference to “arms” does
not apply “only [to] those arms in existence in the 18th cen-
tury.”  554  U. S.,  at  582.    “Just  as  the  First  Amendment 
protects modern forms of communications, and the Fourth
Amendment applies to modern forms of search, the Second
Amendment  extends,  prima  facie,  to  all  instruments  that
constitute bearable arms, even those that were not in exist-
ence at the time of the founding.”  Ibid. (citations omitted). 
Thus,  even  though  the  Second  Amendment’s  definition  of
“arms”  is  fixed  according  to  its  historical  understanding, 
that general definition covers modern instruments that fa-
cilitate armed self-defense.  Cf. Caetano v. Massachusetts, 
577 U. S. 411, 411–412 (2016) (per curiam) (stun guns).

Much  like  we  use  history  to  determine  which  modern 
“arms” are protected by the Second Amendment, so too does 
history guide our consideration of modern regulations that 
were unimaginable at the founding.  When confronting such
present-day firearm regulations, this historical inquiry that
courts  must  conduct  will  often  involve  reasoning  by  anal-
ogy—a commonplace task for any lawyer or judge.  Like all