HSC § 11552

In any case in which a person has been arrested for a criminal offense and is suspected of being addicted to a controlled substance, a law enforcement officer having custody of such person may, with the written consent of such person, request the city or county health officer, or physician appointed by such health officer pursuant to Section 11551, to administer to the arrested person a test to determine, by whatever means is available whether the arrested person is addicted to a controlled substance, and such health officer or physician may administer such test to such arrested person.