The Supreme Court ruled that police don't need warrants for breath tests, but they do for blood tests. | Getty Supreme Court limits state laws on driver blood-alcohol tests

The Supreme Court on Thursday limited state laws that make it a crime for suspected drunk drivers to refuse alcohol tests.

Justices ruled in a series of three cases from Minnesota and North Dakota challenging so-called "implied-consent" laws that police need a search warrant before asking drivers to take a blood alcohol test but also decided that warrants are not needed for breath tests measuring alcohol content.


"The impact of breath tests on privacy is slight, and the need for BAC testing is great," Justice Samuel Alito wrote in the majority opinion. "We reach a different conclusion with respect to blood tests. Blood tests are significantly more intrusive, and their reasonableness must be judged in light of the availability of the less invasive alternative of a breath test. Respondents have offered no satisfactory justification for demanding the more intrusive alternative without a warrant."

Justices Sonia Sotomayor and Ruth Bader Ginsburg partially dissented, saying they would hold that neither blood nor breath tests be allowed without a search warrant, while Justice Clarence Thomas said he would allow both regardless of whether a warrant is obtained.