In Medical Malpractice Overview, medical expert witness Eugene DeBlasio writes on unauthorized treatment or lack of informed consent:
Virtually all states have recognized, either by express STATUTE or COMMON LAW, the right to receive information about one's medical condition, the treatment choices, risks associated with the treatments, and prognosis. The information must be in plain language terms that can readily be understood and in sufficient amounts such that a patient is able to make an "informed" decision about his or her health care. If the patient has received this information, any consent to treatment that is given will be presumed to be an "informed consent." A doctor who fails to obtain INFORMED CONSENT for non-emergency treatment may be charged with a civil and/or criminal offense such as a "battery" or an unauthorized touching of the plaintiff's person.
In order to prevail on a charge that a doctor performed a treatment or procedure without "informed consent," the patient must usually show that, had the patient known of the risk or outcome allegedly not disclosed, the patient would not have opted for the treatment or procedure and thus avoided the risk. In other words, the patient must show a harmful consequence to the unauthorized treatment.