Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 2

2 

CARPENTER v. UNITED STATES 

Syllabus 

prepared  to  recognize  as  reasonable,”  official  intrusion  into  that 
sphere  generally  qualifies  as  a  search  and  requires  a  warrant  sup-
ported by probable cause.  Smith v. Maryland, 442 U. S. 735, 740 (in-
ternal  quotation  marks  and  alterations  omitted).    The  analysis  re-
garding  which  expectations  of  privacy  are  entitled  to  protection  is 
informed  by  historical  understandings  “of  what  was  deemed  an  un-
reasonable  search  and  seizure  when  [the  Fourth  Amendment]  was 
adopted.”  Carroll v. United States, 267 U. S. 132, 149.  These Found-
ing-era understandings continue to inform this Court when applying 
the Fourth Amendment to innovations in surveillance tools.  See, e.g., 
Kyllo v. United States, 533 U. S. 27.  Pp. 4–7. 

(b) The  digital  data  at  issue—personal  location  information
maintained by a third party—does not fit neatly under existing prec-
edents but lies at the intersection of two lines of cases.  One set ad-
dresses a person’s expectation of privacy in his physical location and 
movements.  See, e.g., United States v. Jones, 565 U. S. 400 (five Jus-
tices concluding that privacy concerns would be raised by GPS track-
ing).  The other addresses  a person’s expectation of privacy in infor-
mation voluntarily turned over to third parties.  See United States v. 
Miller,  425  U. S.  435  (no  expectation  of  privacy  in  financial  records 
held by a bank), and Smith, 442 U. S. 735 (no expectation of privacy 
in records of dialed telephone numbers conveyed to telephone compa-
ny).  Pp. 7–10.

(c) Tracking  a  person’s  past  movements  through  CSLI  partakes
of many of the qualities of GPS monitoring considered in Jones—it is 
detailed,  encyclopedic,  and  effortlessly  compiled.    At  the  same  time, 
however,  the  fact  that  the  individual  continuously  reveals  his  loca-
tion  to  his  wireless  carrier  implicates  the  third-party  principle  of 
Smith and  Miller.    Given  the  unique  nature  of  cell-site  records,  this
Court declines to extend Smith and Miller to cover them.  Pp. 10–18. 
(1) A  majority  of  the  Court  has  already  recognized  that  indi-
viduals have a reasonable expectation of privacy in the whole of their 
physical  movements.    Allowing  government  access  to  cell-site  rec-
ords—which “hold for many Americans the ‘privacies of life,’ ” Riley v. 
California, 573 U. S. ___, ___—contravenes that expectation.  In fact, 
historical cell-site records present even greater privacy concerns than 
the  GPS  monitoring considered  in Jones: They give  the Government
near perfect surveillance and allow it to travel back in time to retrace 
a  person’s  whereabouts,  subject  only  to  the  five-year  retention  poli-
cies  of  most  wireless  carriers.    The  Government  contends  that  CSLI 
data is less precise than GPS information, but it thought the data ac-
curate  enough  here  to  highlight  it  during  closing  argument  in  Car-
penter’s trial.  At any rate, the rule the Court adopts “must take ac-
count  of  more  sophisticated  systems  that  are  already  in  use  or  in