Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 116.0

18 

CARPENTER v. UNITED STATES 

GORSUCH, J., dissenting 

Ex parte  Jackson  reflects  that  understanding.   There  this 
Court  said  that  “[n]o  law  of  Congress”  could  authorize 
letter carriers “to invade the secrecy of letters.”  96 U. S., 
at  733.  So  the  post  office  couldn’t  impose  a  regulation
dictating  that  those  mailing  letters  surrender  all  legal
interests  in  them  once  they’re  deposited  in  a  mailbox.    If 
that is right, Jackson suggests the existence of a constitu-
tional  floor  below  which  Fourth  Amendment  rights  may 
not descend.  Legislatures cannot pass laws declaring your
house  or  papers  to  be  your  property  except  to  the  extent 
the  police  wish  to  search  them  without  cause.    As  the 
Court has previously explained, “we must ‘assur[e] preser-
vation  of  that  degree  of  privacy  against  government  that
existed  when  the  Fourth  Amendment  was  adopted.’ ” 
Jones,  565  U. S.,  at  406  (quoting  Kyllo  v.  United  States, 
533  U. S.  27,  34  (2001)).    Nor  does  this  mean  protecting
only  the  specific  rights  known  at  the  founding;  it  means 
protecting  their  modern  analogues  too.  So,  for  example, 
while  thermal  imaging  was  unknown  in  1791,  this  Court 
has recognized that using that technology to look inside a 
home  constitutes  a  Fourth  Amendment  “search”  of  that 
“home”  no  less  than  a  physical  inspection  might.    Id., 
at 40. 

Fifth,  this  constitutional  floor  may,  in  some  instances,
bar efforts to circumvent the Fourth Amendment’s protec-
tion  through  the  use  of  subpoenas.    No  one  thinks  the 
government  can  evade  Jackson’s  prohibition  on  opening 
sealed letters without a warrant simply by issuing a sub-
poena to a postmaster for “all letters sent by John Smith” 
or,  worse,  “all  letters  sent  by  John  Smith  concerning  a
particular  transaction.”  So  the  question  courts  will  con-
front  will  be  this:  What  other  kinds  of  records  are  suffi-
ciently  similar  to  letters  in  the  mail  that  the  same  rule 
should apply?

It may be that, as an original matter, a subpoena requir-
ing the recipient to produce records wasn’t thought of as a