Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 3

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

3 

Syllabus 

development,”  Kyllo,  533  U. S.,  at  36,  and  the  accuracy  of  CSLI  is
rapidly approaching GPS-level precision.  Pp. 12–15. 

(2) The  Government  contends  that  the  third-party  doctrine 
governs this case, because cell-site records, like the records in Smith 
and  Miller,  are  “business  records,”  created  and  maintained  by  wire-
less  carriers.  But  there  is  a  world  of  difference  between  the  limited 
types of personal information addressed in Smith and Miller and the 
exhaustive  chronicle  of  location  information  casually  collected  by
wireless carriers. 

The third-party doctrine partly stems from the notion that an indi-
vidual has a reduced expectation of privacy in information knowingly 
shared with another.  Smith and Miller, however, did not rely solely 
on the act of sharing.  They also considered “the nature of the partic-
ular  documents  sought”  and  limitations  on  any  “legitimate  ‘expecta-
tion of privacy’ concerning their contents.”  Miller, 425 U. S., at 442. 
In  mechanically  applying  the  third-party  doctrine  to  this  case  the 
Government fails to appreciate the lack of comparable limitations on
the revealing nature of CSLI. 

Nor  does  the  second  rationale  for  the  third-party  doctrine—
voluntary exposure—hold up when it comes to CSLI.  Cell phone lo-
cation  information  is  not  truly  “shared”  as  the  term  is  normally  un-
derstood.  First, cell phones and the services they provide are “such a 
pervasive  and  insistent  part  of  daily  life”  that  carrying  one  is  indis-
pensable to participation in modern society.  Riley, 573 U. S., at ___. 
Second,  a  cell  phone  logs  a  cell-site  record  by  dint  of  its  operation,
without  any  affirmative  act  on  the  user’s  part  beyond  powering  up.
Pp. 15–17. 

(d) This decision is narrow.  It does not express a view on matters 
not  before  the  Court;  does  not  disturb  the  application  of  Smith  and 
Miller or call into question conventional surveillance techniques and 
tools, such as security cameras; does not address other business rec-
ords that might incidentally reveal location information; and does not
consider  other  collection  techniques  involving  foreign  affairs  or  na-
tional security.  Pp. 17–18.

2.  The Government did not obtain a warrant supported by proba-
ble  cause  before  acquiring  Carpenter’s  cell-site  records.    It  acquired 
those records pursuant to a court order under the Stored Communi-
cations  Act,  which  required  the  Government  to  show  “reasonable
grounds” for believing that the records were “relevant and material to 
an  ongoing  investigation.”    18  U. S. C.  §2703(d).    That  showing  falls
well short of the probable cause required for a warrant.  Consequent-
ly, an order issued under §2703(d) is not a permissible mechanism for
accessing  historical  cell-site  records.    Not  all  orders  compelling  the
production of documents will require a showing of probable cause.  A