Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 69

Cite as:  585 U. S. ____ (2018) 

19 

THOMAS, J., dissenting 

Right to Privacy, 45 Brandeis L. J. 643, 650 (2007) (“[Un­
der Katz, t]he government seemingly can deny privacy just 
by letting people know in advance not to expect any”).  A 
purely  descriptive  understanding  of  the  Katz  test  also 
risks  “circular[ity].”    Kyllo,  533  U. S.,  at  34.  While  this 
Court is supposed to base its decisions on society’s expec­
tations of privacy, society’s expectations of privacy are, in 
turn,  shaped  by  this  Court’s  decisions.    See  Posner,  The 
Uncertain  Protection  of  Privacy  by  the  Supreme  Court, 
1979  S. Ct.  Rev.  173,  188  (“[W]hether  [a  person]  will  or 
will  not  have  [a  reasonable]  expectation  [of  privacy]  will 
depend on what the legal rule is”).

To  address  this  circularity  problem,  the  Court  has  in­
sisted that expectations of privacy must come from outside
its Fourth Amendment precedents, “either by reference to 
concepts of real or personal property law or to understand­
ings that are recognized and permitted by society.”  Rakas 
v.  Illinois,  439  U. S.  128,  144,  n. 12  (1978).    But  the 
Court’s  supposed  reliance  on  “real  or  personal  property 
law”  rings  hollow.  The  whole  point  of  Katz  was  to  “ ‘dis­
credi[t]’ ” the relationship between the Fourth Amendment
and  property  law,  389  U. S.,  at  353,  and  this  Court  has
repeatedly  downplayed  the  importance  of  property  law 
under  the  Katz  test,  see,  e.g.,  United  States  v.  Salvucci, 
448 U. S. 83, 91 (1980) (“[P]roperty rights are neither the 
beginning  nor  the  end  of  this  Court’s  inquiry  [under 
Katz]”);  Rawlings  v.  Kentucky,  448  U. S.  98,  105  (1980) 
(“[This  Court  has]  emphatically  rejected  the  notion  that
‘arcane’  concepts  of  property  law  ought  to  control  the 
ability  to  claim  the  protections  of  the  Fourth  Amend­
ment”).  Today, for example, the Court makes no mention 
of property law, except to reject its relevance.  See ante, at 
5, and n. 1. 

As for “understandings that are recognized or permitted
in  society,”  this  Court  has  never  answered  even  the  most 
basic  questions  about  what  this  means.    See  Kerr,  Four