Document ID: ./input/supremecourt_opinions/opinions/14pdf/13-9972_p8k0.pdf
Page Number: 20

Cite as:  575 U. S. ____ (2015) 

7 

THOMAS, J., dissenting 

ering  that  problem,  is  not  treated  as  a  traffic-based  in-
quiry.  Warrant  checks,  arguably,  should  fare  no  better.
The majority suggests that a warrant check is an ordinary 
inquiry incident to a traffic stop because it can be used “ ‘to 
determine whether the apparent traffic violator is wanted 
for  one  or  more  previous  traffic  offenses.’ ”    Ante,  at  6 
(quoting  4  W.  LaFave,  Search  and  Seizure  §9.3(c),  p.  516 
(5th  ed.  2012)).  But  as  the  very  treatise  on  which  the 
majority relies notes, such checks are a “manifest[ation of]
the ‘war on drugs’ motivation so often underlying [routine 
traffic] stops,” and thus are very much like the dog sniff in
this case.  Id., §9.3(c), at 507–508.

Investigative questioning rests on the same basis as the 
dog sniff.  “Asking questions is an essential part of police
investigations.”  Hiibel  v.  Sixth  Judicial  Dist.  Court  of 
Nev.,  Humboldt  Cty.,  542  U. S.  177,  185  (2004).    And  the 
lower  courts  have  routinely  upheld  such  questioning  dur-
ing routine traffic stops.  See, e.g., United States v. Rivera, 
570 F. 3d 1009, 1013 (CA8 2009); United States v. Childs, 
277  F. 3d  947,  953–954  (CA7  2002).    The  majority’s  rea-
soning  appears  to  allow  officers  to  engage  in  some  ques-
tioning  aimed  at  detecting  evidence  of  ordinary  criminal 
wrongdoing.  Ante,  at  5.    But  it  is  hard  to  see  how  such 
inquiries  fall  within  the  “seizure’s  ‘mission’  [of ]  ad-
dress[ing] the traffic violation that warranted the stop,” or
“attend[ing] to related safety concerns.”  Ibid.  Its reason-
ing  appears  to  come  down  to  the  principle  that  dogs  are 
different. 

C 

On  a  more  fundamental  level,  the  majority’s  inquiry 
elides the distinction between traffic stops based on prob-
able  cause  and  those  based  on  reasonable  suspicion. 
Probable  cause  is  the  “traditional  justification”  for  the 
seizure  of  a  person.    Whren,  517  U. S.,  at  817  (emphasis
deleted);  see  also  Dunaway  v.  New  York,  442  U. S.  200,