WASHINGTON (Reuters) - The Supreme Court on Wednesday limited the ability of police to take involuntary blood samples from suspected drunken drivers without a search warrant.
The court voted 8-1 on the general point that police cannot always take blood samples without a warrant. But the justices disagreed on what kind of guidance they should give police on when a warrant is necessary.
In reaching its conclusion, the court said a blood test administered to a Missouri driver without a warrant violated his right to be free from unreasonable search and seizures under the Fourth Amendment to the U.S. Constitution.
Missouri state police administered the test after the driver, Tyler McNeely, refused to submit to a breathalyzer test.
Only three of the nine justices agreed in full with Justice Sonia Sotomayor's majority opinion.
Justice Anthony Kennedy joined with most of Sotomayor's reasoning and wrote a concurring opinion. Chief Justice John Roberts wrote a separate opinion agreeing in part with Sotomayor and was joined by Justice Stephen Breyer and Justice Samuel Alito. Justice Clarence Thomas wrote a dissenting opinion.
Sotomayor wrote that concerns over the natural dissipation of alcohol in the bloodstream does not "in every case" give police a compelling reason "sufficient to justify conducting a blood test without a warrant."
She noted that the "relevant factors" for police to consider when deciding whether a warrant is needed include whether there is time to obtain a warrant before the evidence is lost.
The determination "will no doubt vary depending on the circumstances," she added.
Sotomayor noted that in the Missouri case there were no special circumstances that prevented the officer from seeking a warrant. The state did not argue that there was not time to obtain a warrant.
Kennedy said in his opinion that, in his view, the case gave the court little opportunity to provide a more detailed framework for police to follow.
Roberts noted in his opinion that a police officer reading the court's conclusions would have "no idea" how to avoid violating the Fourth Amendment. He, Breyer and Alito would have ruled that police officers must seek a warrant only if there is time to do so.
McNeely's blood-alcohol content was measured at 0.154 percent, nearly twice Missouri's legal limit, and the state had argued, on behalf of the police, that blood tests were an effective way to obtain evidence of drunken driving.
It said this evidence could vanish in the time it took to obtain a warrant because alcohol quickly dissipates in the bloodstream.
The upshot of Wednesday's ruling is that in McNeely's case and others like it, police would not be able to use a blood test as evidence without first getting a warrant.
The case is Missouri v. McNeely, U.S. Supreme Court, No. 11-1425.
(Reporting by Lawrence Hurley; Editing by Howard Goller, Christopher Wilson and Cynthia Osterman)