Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 19

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

15 

Opinion of the Court 

the  capability  to  pinpoint  a  phone’s  location  within  50 
meters.  Brief for Electronic Frontier Foundation et al. as 
Amici  Curiae  12  (describing  triangulation  methods  that 
estimate a device’s location inside a given cell sector).

Accordingly, when the Government accessed CSLI from
the  wireless  carriers,  it  invaded  Carpenter’s  reason-
able  expectation  of  privacy  in  the  whole  of  his  physical 
movements. 

B 
The Government’s primary contention to the contrary is
that  the  third-party  doctrine  governs  this  case.    In  its 
view,  cell-site  records  are  fair  game  because  they  are
“business records” created and maintained by the wireless
carriers.  The Government (along with JUSTICE KENNEDY)
recognizes  that  this  case  features  new  technology,  but 
asserts  that  the  legal  question  nonetheless  turns  on  a 
garden-variety  request  for  information  from  a  third-party
witness.  Brief for United States 32–34; post, at 12–14. 

The  Government’s  position  fails  to  contend  with  the
seismic shifts in digital technology that made possible the 
tracking of not only Carpenter’s location but also everyone 
else’s,  not  for  a  short  period  but  for  years  and  years.
Sprint  Corporation  and  its  competitors  are  not  your  typi-
cal witnesses.  Unlike the nosy neighbor who keeps an eye 
on  comings  and  goings,  they  are  ever  alert,  and  their 
memory is nearly infallible.  There is a world of difference 
between  the  limited  types  of  personal  information  ad-
dressed in Smith and Miller and the exhaustive chronicle 
of  location  information  casually  collected  by  wireless
carriers  today.    The  Government  thus  is  not  asking  for  a
straightforward  application  of  the  third-party  doctrine, 
but instead a significant extension of it to a distinct cate-
gory of information.

The  third-party  doctrine  partly  stems  from  the  notion 
that an individual has a reduced expectation of privacy in