Police must obtain a search warrant to draw blood to get evidence of drunken driving, the U.S. Supreme Court said today in a divided opinion.
In the case before the court, Tyler G. McNeely had been pulled over in Cape Girardeau County, Mo., in 2010 with an alleged blood alcohol level of 0.154.
Shortly before McNeely’s arrest, state lawmakers had amended Missouri’s driving while intoxicated statutes in a way that arguably allowed police officers to obtain nonconsensual chemical samples without a warrant.
This morning, the U.S. Supreme Court rejected the state’s request for a bright-line rule permitting warrantless blood draws. The state had argued that evidence of blood-alcohol content naturally dissipates over time, creating an exigent, or emergency, circumstance entitling police to gather the evidence without a warrant.
“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,” Justice Sonia Sotomayor wrote for the majority.
Chief Justice John Roberts wrote a separate opinion concurring in part and dissenting in part, while Justice Clarence Thomas dissented.
The case is Missouri v. McNeely, 11-1425.
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