In a divided opinion, the court made a distinction between blood tests, which require the piercing of the skin, and breath tests, which it found are not particularly painful, intrusive or embarrassing.
The Supreme Court ruled that police should obtain a warrant for most DUI blood tests prior to drawing the blood. Unlike a breathalyzer test, which utilizes air that a suspect would normally breathe out, a blood test is invasive and violates the Constitution's Fourth Amendment against unreasonable searches and seizures, the justices found. And unlike a breathalyzer test, a blood test gives law enforcement a sample that can be preserved and from which other personal information might be extracted, the justices wrote.
Justice Samuel A. Alito Jr., in a part of the decision determined by a 7-to-1 vote, said laws effectively requiring blood tests violated the Fourth Amendment’s ban on unreasonable searches. In a part decided by a 6-to-2 vote, Justice Alito wrote that laws requiring breath tests are permissible.
In a partial dissent, Justice Sonia Sotomayor, joined by Justice Ruth Bader Ginsburg, said warrants should be required for both kinds of tests.
“The court lacks even the pretense of attempting to situate breath searches within the narrow and weighty law enforcement needs that have historically justified the limited use of warrantless searches,” Justice Sotomayor wrote. “I fear that if the court continues down this road, the Fourth Amendment’s warrant requirement will become nothing more than a suggestion.”
In a second partial dissent, Justice Clarence Thomas said he would not have required a warrant for either kind of search.