Petitioner Gerald Mitchell’s blood was drawn while he was unconscious at the direction of the police after he was arrested on suspicion of drunk driving. The police did not have a warrant and conceded that no exigent circumstances prevented them from obtaining one. The state argued that no warrant was required because its “implied-consent law” authorizes the police to draw blood from an unconscious motorist if they have probable cause to suspect drunk driving.

The ACLU and the ACLU of Wisconsin filed an amicus brief in support of Mr. Mitchell arguing that the Fourth Amendment requires that consent be free and voluntary, and an unconscious person cannot freely and voluntarily consent to a search, any purported “implied-consent” statute, which simply presumes that all drivers on Wisconsin roads have consented to such a search, does not establish that an individual has in fact consented as a Fourth Amendment matter to a particular search. For consent to a search to be truly voluntary, the individual providing consent must have the freedom to change her mind — including by denying or revoking consent. Because an unconscious person cannot make a choice at all, the state cannot constitutionally impute an irrevocable presumption of “consent” on an unconscious person merely because he has driven on the state’s roads.


US Supreme Court