Supreme Court: Police Usually Need Warrant for Blood Alcohol Tests

The U.S. Supreme Court ruled this week that police generally need a search warrant before they order a blood alcohol test for someone suspected of drunk driving.

The case centered on Tyler McNeely, who was pulled over for speeding by a Missouri highway patrolman, and was taken to a hospital. About 25 minutes after McNeely was pulled over, a technician measured his blood-alcohol content at 0.154 percent, nearly twice the legal limit.

The Missouri police in the case argued they should not have to wait for approval to give a blood test, because alcohol dissipates quickly in the bloodstream. Last year, the Missouri Supreme Court rejected that argument. It ruled the blood test violated the Fourth Amendment. The court found there were no special circumstances to justify obtaining the blood test so quickly. State high courts in Iowa and Utah also have made similar rulings.

Writing for the Supreme Court, Justice Sonia Sotomayor noted the natural dissipation of alcohol in the blood is generally not sufficient reason to abandon the requirement that police get a judge’s approval before obtaining a blood sample.

Warrantless blood tests are prohibited in about half the states in most or all suspected drunk driving cases, the Associated Press reports.