Imagine this scenario: a person is arrested for OWI/DUI. The officer handcuffs the driver and places them in the back of the police car to drive them to the hospital for a blood draw. By the time the officer arrives at the hospital, the arrested individual is passed out and unconscious. The officer then proceeds to read to this unconscious individual a form, which explains to them that they may refuse the blood draw, which would require the officer to get a warrant signed by a Judge before any blood could be drawn. Of course, the unconscious person does not respond, so the police officer goes forward with a blood draw on this unconscious person without a warrant.
That is exactly what happened to Gerald Mitchell in 2013. He was charged with an OWI and when his lawyer filed motions to fight the blood draw because a warrant had not be sought by the police officer, our Wisconsin Supreme Court ruled in State vs. Mitchell that the warrantless blood draw was perfectly legal. The law in Wisconsin states that if you have a drivers license or you are driving on the roadways of Wisconsin you have consented (or consent is implied) to provide a sample of your blood should you be arrested for an OWI. Therefore, the majority of our Wisconsin Supreme Court has decided that if you become unconscious as a result of consuming alcohol, then you forfeit your right to withdraw consent. Two of our Supreme Court Justices disagreed, explaining that since blood draws are particularly intrusive, then consent to a blood draw must be more than just implied.