Document ID: ./input/supremecourt_opinions/opinions/12pdf/11-1425_cb8e.pdf
Page Number: 43

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

3 

THOMAS, J., dissenting 

explained  that  drawing  a  person’s  blood  is  “a  highly  ef- 
fective  means  of  determining  the  degree  to  which  [he]  is 
under  the  influence  of alcohol”  and  is  a  reasonable  proce­
dure because blood tests are “commonplace” and “involv[e]
virtually no risk, trauma, or pain.”1  384 U. S., at 771.  The 
Court,  therefore,  held  that  dissipation  of  alcohol  in  the
blood  constitutes  an  exigency  that  allows  a  blood  draw 
without a warrant. 

The  rapid  destruction  of  evidence  acknowledged  by  the 

parties,  the  majority,  and  Schmerber’s  exigency  determi­
nation occurs in every situation where police have probable
cause  to  arrest  a  drunk  driver.    In  turn,  that  destruction 
of evidence implicates the exigent-circumstances doctrine.
See  Cupp  v.  Murphy,  412  U. S.  291  (1973).    In  Cupp, 
officers  questioning  a  murder  suspect  observed  a  spot  on
the  suspect’s  finger  that  they  believed  might  be  dried
blood.  Id., at  292.  After  the  suspect  began  making  obvi­
ous efforts to remove the spots from his hands, the officers
took  samples  without  obtaining  either  his  consent  or  a 
warrant.    Id.,  at  296.  Following  a  Fourth  Amendment 
challenge  to  this  search,  the  Court  held  that  the  “ready
destructibility of the evidence” and the suspect’s observed
efforts  to  destroy  it  “justified  the  police  in  subjecting  him
to the very limited search necessary to preserve the highly 
evanescent  evidence  they  found  under  his  fingernails.” 
Ibid. 

In  this  case,  a  similar  exigency  is  present.    Just  as  the 
suspect’s  efforts  to  destroy  “highly  evanescent  evidence” 
gave rise to the exigency in Cupp, the natural metaboliza­
tion  of  blood  alcohol  concentration  (BAC)  creates  an  exi­
gency once police have probable cause to believe the driver 

—————— 

1 Neither  party  has  challenged  this  determination,  which  this  Court
has  reaffirmed  several  times.  See,  e.g.,  Skinner  v.  Railway  Labor 
Executives’  Assn.,  489  U. S.  602,  625  (1989);  Winston  v.  Lee,  470  U. S. 
753, 761–763 (1985).