The U.S. Supreme Court outlined new parameters for testing suspected drunk drivers on Thursday, ruling that the Fourth Amendment allows warrantless breath tests but forbids warrantless blood tests.
“The impact of breath tests on privacy is slight, and the need for BAC [blood alcohol content] testing is great,” Justice Samuel Alito wrote for the Court in Birchfield v. North Dakota and its consolidated cases. “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.”
The Court combined three cases from lower courts in the Midwest for its ruling. All of them involved state laws criminalizing the refusal of blood and breath BAC tests. In North Dakota, Danny Birchfield received a 30-day sentence and fine for refusing a warrantless blood test and Michael Baylund lost his drivers’ license after officers told him refusing a warrantless blood test was a crime. In Minnesota, William Bernard challenged his prosecution after refusing a warrantless breath test.
Writing for the Court, Alito analyzed the tests under the Fourth Amendment’s search-incident-to-arrest exception. As its name suggests, the rule allows police officers to search a person’s body and immediate surroundings without a warrant after their lawful arrest. Breath BAC tests, he wrote, don’t rise to the level of intrusiveness the Fourth Amendment protects: they leave no permanent sample in the government’s possession and don’t undermine the arrestee’s dignity in any significant way.