A blog of the Philadelphia Bar Association’s Criminal Justice Section


By Burt Rose

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THE SUPREME COURT OF THE UNITED STATES has decided the matter of MISSOURI, PETITIONER v. TYLER G. MCNEELY, No. 11–1425 (April 17, 2013). JUSTICE SOTOMAYOR delivered the opinion of the Court in which JUSTICE SCALIA, JUSTICE GINSBURG, and JUSTICE KAGAN joined in part.


In Schmerber v. California, 384 U. S. 757 (1966), the Court upheld a warrantless blood test of an individual arrested for driving under the influence of alcohol because the officer might reasonably have believed that he was confronted with an emergency, in which the delay necessary to obtain a warrant, under the circumstances, threatened the destruction of evidence. The question presented here was whether the natural metabolization of alcohol in the bloodstream presents a per se exigency that justifies an exception to the Fourth Amendment’s warrant requirement for nonconsensual blood testing in all drunk-driving cases. The Court concluded that it does not and  held that exigency in this context must be determined case by case based on the totality of the circumstances.


The Court rejected the State’s argument that so long as an officer has probable cause and the blood test is conducted in a reasonable manner, it is categorically reasonable for law enforcement to obtain the blood sample without a warrant. Although it is true that because an individual’s alcohol level gradually declines soon after he stops drinking, a significant delay in testing will negatively affect the probative value of the results, in those drunk-driving investigations where police officers can reasonably obtain a warrant before a blood sample can be drawn without significantly undermining the efficacy of the search, the Fourth Amendment mandates that they do so. The Court noted however that exigent circumstances justifying a warrantless blood sample may arise in the regular course of law enforcement due to delays from the warrant application process. Whether a warrantless blood test of a drunk-driving suspect is reasonable must be determined case by case based on the totality of the circumstances; the metabolization of alcohol in the bloodstream and the ensuing loss of evidence are among the factors that must be considered in deciding whether a warrant is required.


Thus the Court held that in drunk-driving investigations, the natural dissipation of alcohol in the bloodstream does not constitute an exigency in every case sufficient to justify conducting a blood test without a warrant.



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