Document ID: ./input/supremecourt_opinions/opinions/17pdf/16-402_h315.pdf
Page Number: 108

10 

CARPENTER v. UNITED STATES 

GORSUCH, J., dissenting 

as evidence of the people’s habits and reasonable expecta-
tions  of  privacy,  the  Court  substituted  its  own  curious
judgment.
  Resorting  to  Katz  in  data  privacy  cases  threatens  more 
of  the  same.  Just  consider.  The  Court  today  says  that 
judges should use Katz’s reasonable expectation of privacy
test to decide what Fourth Amendment rights people have 
in cell-site location information, explaining that “no single
rubric  definitively  resolves  which  expectations  of  privacy 
are entitled to protection.”  Ante, at 5.  But then it offers a 
twist.  Lower  courts  should  be  sure  to  add  two  special
principles  to  their  Katz  calculus:  the  need  to  avoid  “arbi-
trary power” and the importance of “plac[ing] obstacles in 
the way of a too permeating police surveillance.”  Ante, at 
6 (internal quotation marks omitted).  While surely lauda-
ble,  these  principles  don’t  offer  lower  courts  much  guid-
ance.  The Court does not tell us, for example, how far to
carry  either  principle  or  how  to  weigh  them  against  the
legitimate  needs  of  law  enforcement.    At  what  point  does
access  to  electronic  data  amount  to  “arbitrary”  authority?
When  does  police  surveillance  become  “too  permeating”? 
And  what  sort  of  “obstacles”  should  judges  “place”  in  law 
enforcement’s path when it does?  We simply do not know. 
The Court’s application of these principles supplies little
more direction.  The Court declines to say whether there is
any sufficiently limited period of time “for which the Gov-
ernment  may  obtain  an  individual’s  historical  [location
information]  free  from  Fourth  Amendment  scrutiny.” 
Ante,  at  11,  n. 3;  see  ante,  at  11–15.    But  then  it  tells  us 
that  access  to  seven  days’  worth  of  information  does  trig-
ger  Fourth  Amendment  scrutiny—even  though  here  the 
carrier “produced only two days of records.”  Ante, at 11, n. 
3.  Why is the relevant fact the seven days of information
the government asked for instead of the two days of infor-
mation  the  government  actually  saw?    Why  seven  days 
instead of ten or three or one?  And in what possible sense