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Page Number: 11.0

8 

RODRIGUEZ v. UNITED STATES 

Opinion of the Court 

tions taken in order to facilitate such detours.  But cf. post,
at  2–3  (ALITO,  J.,  dissenting).  Thus,  even  assuming  that 
the  imposition  here  was  no  more  intrusive  than  the  exit 
order in Mimms, the dog sniff could not be justified on the 
same  basis.    Highway  and  officer  safety  are  interests
different  in  kind  from  the  Government’s  endeavor  to  de­
tect crime in general or drug trafficking in particular. 

The Government argues that an officer may “incremen­
tal[ly]” prolong a stop to conduct a dog sniff so long as the
officer is reasonably diligent in pursuing the traffic-related 
purpose  of  the  stop,  and  the  overall  duration  of  the  stop 
remains  reasonable  in  relation  to  the  duration  of  other 
traffic  stops  involving  similar  circumstances.    Brief  for 
United  States  36–39.    The  Government’s  argument,  in
effect,  is  that  by  completing  all  traffic-related  tasks  expe­
ditiously,  an  officer  can  earn  bonus  time  to  pursue  an
unrelated  criminal  investigation.  See  also  post,  at  2–5 
(THOMAS,  J.,  dissenting)  (embracing  the  Government’s
argument).    The  reasonableness  of  a  seizure,  however, 
depends  on  what  the  police  in  fact  do.    See  Knowles,  525 
In  this  regard,  the  Government 
U. S.,  at  115–117. 
acknowledges that “an officer always has to be reasonably 
diligent.”  Tr.  of  Oral  Arg.  49.    How  could  diligence  be 
gauged other than by noting what the officer actually did 
and how he did it?  If an officer can complete traffic-based
inquiries  expeditiously,  then  that  is  the  amount  of  “time 
reasonably  required  to  complete  [the  stop’s]  mission.” 
Caballes,  543  U.  S.,  at  407.    As  we  said  in  Caballes  and 
reiterate  today,  a  traffic  stop  “prolonged  beyond”  that
point  is  “unlawful.”  Ibid.    The  critical  question,  then,  is 
not whether the dog sniff occurs before or after the officer 
issues  a  ticket,  as  JUSTICE  ALITO  supposes,  post,  at  2–4, 
but  whether  conducting  the  sniff  “prolongs”—i.e.,  adds 
time to—“the stop,” supra, at 6.