The majority opinion continued in relevant part: Schmerber demonstrates that an exigency exists when (1) BAC evidence is dissipating and (2) some other factor creates pressing health, safety, or law enforcement needs that would take priority over a warrant application. Because both conditions are met when a drunk-driving suspect is unconscious, Schmerber controls. A driver’s unconsciousness does not just create pressing needs; it is itself a medical emergency. In such a case, as in Schmerber, an officer could “reasonably have believed that he was confronted with an emergency.” 384 U. S., at 771. And in many unconscious-driver cases, the exigency will be especially acute. A driver so drunk as to lose consciousness is quite likely to crash, giving officers a slew of urgent tasks beyond that of securing medical care for the suspect—tasks that would require them to put off applying for a warrant. The time needed to secure a warrant may have shrunk over the years, but it has not disappeared; and forcing police to put off other urgent tasks for even a relatively short period of time may have terrible collateral costs. On remand, Mitchell may attempt to show that his was an unusual case, in which his blood would not have been drawn had police not been seeking BAC information and police could not have reasonably judged that a warrant application would interfere with other pressing needs or duties.
Justice Alito’s opinion turns illogical with regard to the alleged “medical emergency” under the circumstances. First, unconsciousness will often be due to be tired and falling asleep as opposed to intoxication being the primary cause. Second, no one is saying that an unconscious driver should not be arrested and taken off the road when there is probable cause to believe s/he is intoxicated. The issue is whether a warrant should be obtained before their blood is drawn without their consent.
Justice Thomas authored a concurring opinion in which he would apply a per se rule, under which the natural metabolization of alcohol in the blood stream “creates an exigency once police have probable cause to believe the driver is drunk,” regardless of whether the driver is conscious. Missouri v. McNeely, 569 U. S. 141, 178 (THOMAS, J., dissenting). Justice Alito’s opinion was joined by Chief Justice Roberts, Justice Breyer, and Justice Kavanaugh.
In this close 5-4 case, Justice Sotomayor authored a dissent. She was joined by Justices Ginsburg, Kagan, and Gorsuch.