What is the test for informed consent in medical malpractice cases?

The doctrine of informed consent for contemplated procedure has been developed in numerous cases over time. As explained in Berkey v. Anderson (1969) 1 Cal.App.3d 790, 82 Cal.Rptr. 67, which involved the propriety of a nonsuit against a doctor who prescribed a myelogram, "[i]f appellant did not give his informed or knowledgeable consent, the performance of the myelogram would constitute a technical battery for which the defendant would be liable for all damages proximately resulting, whether the myelogram was or was not skillfully performed.... [p] 'A physician violates his duty to his patient and subjects himself to liability if he withholds any facts which are necessary to form the basis of an intelligent consent by the patient to the proposed treatment. Likewise the physician may not minimize known dangers of a procedure or operation in order to induce his patient's consent." (Id., at pp. 803-804, 82 Cal.Rptr. 67, citations omitted.) ⁵