Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 54

4 

CARPENTER v. UNITED STATES 

THOMAS, J., dissenting 

presence or absence of a physical intrusion.”  389 U. S., at 
353.  The  Court  did  not  explain  what  should  replace 
Olmstead’s  physical-intrusion  requirement.    It  simply 
asserted that “the Fourth Amendment protects people, not
places”  and  “what  [a  person]  seeks  to  preserve  as  private 
. . . may be constitutionally protected.”  389 U. S., at 351. 
Justice Harlan’s concurrence in Katz attempted to artic­
ulate  the  standard  that  was  missing  from  the  majority 
opinion.  While  Justice  Harlan  agreed  that  “ ‘the  Fourth 
Amendment protects people, not places,’ ” he stressed that
“[t]he  question  . . .  is  what  protection  it  affords  to  those
people,”  and  “the  answer  . . .  requires  reference  to  a 
‘place.’ ”  Id.,  at  361.  Justice  Harlan  identified  a  “twofold 
requirement”  to  determine  when  the  protections  of  the 
Fourth Amendment apply: “first that a person have exhib­
ited  an  actual  (subjective)  expectation  of  privacy  and,
second,  that  the  expectation  be  one  that  society  is  pre­
pared to recognize as ‘reasonable.’ ”  Ibid. 

Justice  Harlan  did  not  cite  anything  for  this  “expecta­
tion  of  privacy”  test,  and  the  parties  did  not  discuss  it  in
their  briefs.    The  test appears  to  have  been presented  for 
the  first  time  at  oral  argument  by  one  of  the  defendant’s 
lawyers.  See Winn, Katz and the Origins of the “Reason- 
able Expectation of Privacy” Test, 40 McGeorge L. Rev. 1,
9–10  (2009).  The  lawyer,  a  recent  law-school  graduate,
apparently  had  an  “[e]piphany”  while  preparing  for  oral 
argument.  Schneider,  Katz  v.  United  States:  The  Untold 
Story, 40 McGeorge L. Rev. 13, 18 (2009).  He conjectured 
that, like the “reasonable person” test from his Torts class, 
the  Fourth  Amendment  should  turn  on  “whether  a  rea­
sonable person . . . could have expected his communication 
to  be  private.”  Id.,  at  19.  The  lawyer  presented  his  new
theory to the Court at oral argument.  See, e.g., Tr. of Oral 
Arg.  in  Katz  v.  United  States,  O. T.  1967,  No. 35,  p. 5 
(proposing a test of “whether or not, objectively speaking,
the communication was intended to be private”); id., at 11