Supreme Court rules sobriety blood tests require warrants


WASHINGTON — Police officers usually must have a search warrant before requiring a suspected drunk driver to have his blood drawn, the Supreme Court said Wednesday.

In an 8-1 decision, the justices rejected Missouri prosecutors’ contention that police should have the freedom to act quickly and dispense with a warrant because alcohol dissipates in the blood.

Instead, the court said it would hold fast to its view that the 4th Amendment’s ban on “unreasonable searches” means the police usually need a warrant from a magistrate before invading a person’s privacy. And sticking a needle into someone’s veins to obtain a sample of blood “is an invasion of bodily integrity [that] implicates an individual’s most personal and deep-rooted expectations of privacy,” said Justice Sonia Sotomayor.


But she also said that police sometimes need to act fast and in these cases they do not need to wait for a magistrate. For example, an officer may find it hard to obtain a warrant if a driver is arrested late at night in a rural area.

Still, these emergencies should be the exception, not the rule, in ordinary cases, Sotomayor said.

Wednesday’s decision makes little change in the law regarding impaired drivers. In all 50 states, motorists who are stopped on suspicion of drunken driving must consent to a breath or blood test or face the loss of their driver’s license.

Most drivers agree to a breath test. If not, an officer can contact a magistrate and obtain a warrant requiring the motorist to have his blood drawn.

Tyler McNeely, a Missouri man, refused to undergo a breath test after he was stopped for speeding after midnight. Without obtaining a warrant, an officer took him in custody and drove him to a nearby hospital to have his blood drawn by a lab technician. It showed McNeely was intoxicated.

But the Missouri courts threw out the evidence on the grounds that the forced blood test was unconstitutional without a warrant.

In their appeal to the Supreme Court, the state attorneys sought a big win. Rather than argue narrowly that the officer who arrested McNeely had a special need to act fast because it was the middle of the night, the state’s attorney asked the justices to rule that search warrants are never required for blood alcohol tests.

That proved to be a tactical mistake. The justices noted it is usually simple and quick for an officer to get a warrant by phone or computer.

“We hold that in drunk driving investigations, the natural dissipation of the blood does not constitute an emergency in every case sufficient to justify conducting a blood test without a warrant,” Sotomayor said in Missouri vs. McNeely.

Justice Clarence Thomas dissented alone. “Because the body’s natural metabolization of alcohol inevitably destroys evidence of the crime, it constitutes an exigent circumstance” that calls for bypassing a search warrant, he said.