Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 20

16 

CARPENTER v. UNITED STATES 

Opinion of the Court 

information knowingly shared with another.  But the fact 
of  “diminished  privacy  interests  does  not  mean  that  the 
Fourth  Amendment  falls  out  of  the  picture  entirely.” 
Riley, 573 U. S., at ___ (slip op., at 16).  Smith and Miller, 
after all, did not rely solely on the act of sharing.  Instead, 
they  considered  “the  nature  of  the  particular  documents
sought” to determine whether “there is a legitimate ‘expec-
tation  of  privacy’  concerning  their  contents.”    Miller,  425 
U. S., at 442.  Smith pointed out the limited capabilities of 
a  pen  register;  as  explained  in  Riley,  telephone  call  logs
reveal  little  in  the  way  of  “identifying  information.” 
Smith, 442 U. S., at 742; Riley, 573 U. S., at ___ (slip op., 
at 24).  Miller likewise noted that checks were “not confi-
dential  communications  but  negotiable  instruments  to  be
used  in  commercial  transactions.”  425  U. S.,  at  442.  In 
mechanically  applying  the  third-party  doctrine  to  this
case, the Government fails to appreciate that there are no
comparable limitations on the revealing nature of CSLI.   

The  Court  has  in  fact  already  shown  special  solicitude 
for  location  information  in  the  third-party  context. 
In 
Knotts, the Court relied on Smith to hold that an individ-
ual  has  no  reasonable  expectation  of  privacy  in  public
movements  that  he  “voluntarily  conveyed  to  anyone  who 
wanted to look.”  Knotts, 460 U. S., at 281; see id., at 283 
(discussing  Smith).  But  when  confronted  with  more  per-
vasive tracking, five Justices agreed that longer term GPS 
monitoring  of  even  a  vehicle  traveling  on  public  streets 
constitutes  a  search.  Jones,  565  U. S.,  at  430  (ALITO,  J., 
concurring  in  judgment);  id.,  at  415  (SOTOMAYOR,  J., 
concurring).   JUSTICE  GORSUCH  wonders  why  “someone’s
location  when  using  a  phone”  is  sensitive,  post,  at  3,  and 
JUSTICE  KENNEDY  assumes  that  a  person’s  discrete
movements “are not particularly private,” post, at 17.  Yet 
this case is not about “using a phone” or a person’s move-
ment at a particular time.  It is about a detailed chronicle 
of  a  person’s  physical  presence  compiled  every  day,  every