Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 8

4 

CARPENTER v. UNITED STATES 

Opinion of the Court 

site data.  Hess explained that each time a cell phone taps
into the wireless network, the carrier logs a time-stamped 
record of the cell site and particular sector that were used.
With  this  information,  Hess  produced  maps  that  placed
Carpenter’s  phone  near  four  of  the  charged  robberies.    In 
the  Government’s  view,  the  location  records  clinched  the 
case: They confirmed that Carpenter was “right where the 
. . .  robbery  was  at  the  exact  time  of  the  robbery.”    App. 
131  (closing  argument).    Carpenter  was  convicted  on  all
but one of the firearm counts and sentenced to more than 
100 years in prison.

The Court of Appeals for the Sixth Circuit affirmed.  819 
F. 3d 880 (2016).  The court held that Carpenter lacked a
reasonable  expectation  of  privacy  in  the  location  infor-
mation  collected  by  the  FBI  because  he  had  shared  that 
information  with  his  wireless  carriers.  Given  that  cell 
phone  users  voluntarily  convey  cell-site  data  to  their
carriers  as  “a  means  of  establishing  communication,”  the
court concluded that the resulting business records are not
entitled  to  Fourth  Amendment  protection.    Id.,  at  888 
(quoting Smith v. Maryland, 442 U. S. 735, 741 (1979)).

We granted certiorari.  582 U. S. ___ (2017). 

II
 
A 

The  Fourth  Amendment  protects  “[t]he  right  of  the
people  to  be  secure  in  their  persons,  houses,  papers,  and
effects, against unreasonable searches and seizures.”  The 
“basic purpose of this Amendment,” our cases have recog-
nized, “is to safeguard the privacy and security of individ-
uals  against  arbitrary  invasions  by  governmental  offi-
cials.”  Camara  v.  Municipal  Court  of  City  and  County  of 
San  Francisco,  387  U. S.  523,  528  (1967).    The  Founding 
generation crafted the Fourth Amendment as a “response 
to the reviled ‘general warrants’ and ‘writs of assistance’ of
the  colonial  era,  which  allowed  British  officers  to  rum-