Document ID: ./input/supremecourt_opinions/opinions/12pdf/11-1425_cb8e.pdf
Page Number: 30

Cite as:  569 U. S. ____ (2013) 

1 

Opinion of ROBERTS, C. J. 

SUPREME COURT OF THE UNITED STATES 

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No. 11–1425 
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MISSOURI, PETITIONER v. TYLER G. MCNEELY 

ON WRIT OF CERTIORARI TO THE SUPREME COURT OF 

MISSOURI
 

[April 17, 2013] 

CHIEF  JUSTICE  ROBERTS,  with  whom  JUSTICE  BREYER 
and JUSTICE ALITO join, concurring in part and dissenting 
in part. 

A police officer reading this Court’s opinion would have
no  idea—no  idea—what  the  Fourth  Amendment  requires 
of  him,  once  he  decides  to  obtain  a  blood  sample  from  a 
drunk  driving  suspect  who  has  refused  a  breathalyzer 
test.  I  have  no  quarrel  with  the  Court’s  “totality  of  the
circumstances” approach as a general matter; that is what
our cases require.  But the circumstances in drunk driving
cases  are  often  typical,  and  the  Court  should  be  able  to 
offer  guidance  on  how  police  should  handle cases  like  the 
one before us. 

In  my  view,  the  proper  rule  is  straightforward.    Our 
cases  establish  that  there  is  an  exigent  circumstances
exception  to  the  warrant  requirement.  That  exception 
applies  when  there  is  a  compelling  need  to  prevent  the
imminent  destruction  of  important  evidence,  and  there  is 
no  time  to  obtain  a  warrant.  The  natural  dissipation  of
alcohol  in  the  bloodstream  constitutes  not  only  the  immi-
nent  but  ongoing  destruction  of  critical  evidence.    That 
would  qualify  as  an  exigent  circumstance,  except  that
there may be time to secure a warrant before blood can be
drawn.  If there is, an officer must seek a warrant.  If an 
officer  could  reasonably  conclude  that  there  is  not,  the 
exigent circumstances exception applies by its terms, and