People v. Sutherland
In People v. Sutherland, 683 P.2d 1192 (Colo. 1984) the defendant and his driving companion were at the hospital following a fatal automobile collision in which their car collided head-on with another vehicle.
The police officer did not know which of the two had been driving, so he had the hospital staff draw the blood of both of them.
The court concluded that "under the circumstances of this case where two persons each claimed the other was the driver of a vehicle involved in a suspected criminal offense, the officer had reasonable grounds to obtain a blood sample from each suspect. We hold that the officer had probable cause to arrest the defendant and to obtain a blood specimen without the consent of the defendant." Id. at 1196.