SCOTUS: Police Don't Need Warrants for Blood Testing of Unconscious DUI Suspects

The Supreme Court of the United States held that the police usually don't need a warrant for a blood test if the driver is unconscious and therefore can't do a breath test for BAC evidence.

In a 2016 case, the U.S. Supreme Court confirmed that, normally, the police need a warrant in order to make a DUI suspect who doesn't consent to a blood test provide a blood sample. (Birchfield v. North Dakota, 136 S. Ct. 2160 (2016).) But in 2019, the Court decided that the police almost never need a warrant to collect a blood sample if the suspect is unconscious and therefore can't do a breath test for BAC evidence. (Mitchell v. Wisconsin, 139 S. Ct. 2525 (2019).)

In the case involved in the 2019 decision, an officer in Wisconsin had received a report that a seemingly very drunk man was driving a van. The officer soon found the man wandering near a lake. The man was stumbling and slurring his words; he could hardly stand. The officer gave him a preliminary breath test, which showed a blood alcohol concentration (BAC) that, at 0.24%, was three times the state's legal limit.

The officer arrested the man for DUI and drove him to the police station for a more reliable breath test, which is sometimes referred to as a "standard evidentiary" breath test. The man was too lethargic for a breath test, so the officer took him to a hospital for a blood test. The man lost consciousness during the drive to the hospital.

At the hospital, the officer read the man—who was, again, unconscious—a standard statement giving drivers an opportunity to refuse BAC testing. Obviously, the officer got no response; he then asked hospital staff to take a blood sample. They did, and its BAC readout of 0.22% was still far above the limit.

The Supreme Court cited the "exigent circumstances" exception to the general Fourth Amendment requirement that police get a warrant before performing a search. In essence, the theory is that, as time wears on, evidence of drunk driving disappears in that the driver's BAC gradually returns to normal. To the Court, the disappearing evidence creates an emergency-like situation that normally justifies officers not waiting for a warrant before getting the blood of an unconscious driver.

For more on the legal rule from this case and its limitations, and also for rules on refusal, see our article about DUI testing.

Effective date: June 27, 2019