How has consent been vitiated in medical malpractice cases?

31 In Reibl v. Hughes, 1980 CanLII 23 (SCC), [1980] 2 S.C.R. 880, 114 D.L.R. (3d) 1, 14 C.C.L.T. 1, 33 N.R. 361, Laskin C.J.C. said (at 891-92 S.C.R.): In situations where the allegation is that attendant risks which should have been disclosed were not communicated to the patient and yet the surgery or other medical treatment carried out was that to which the plaintiff consented (there being no negligence basis of liability for the recommended surgery or treatment to deal with the patient's condition), I do not understand how it can be said that the consent was vitiated by the failure of disclosure so as to make the surgery or other treatment an unprivileged, unconsented to and intentional invasion of the patient's bodily integrity. I can appreciate the temptation to say that the genuineness of consent to medical treatment depends on proper disclosure of the risks which it entails, but in my view, unless there has been misrepresentation or fraud to secure consent to the treatment, a failure to disclose the attendant risks, however serious, should go to negligence rather than to battery. Although such a failure relates to an informed choice of submitting to or refusing recommended and appropriate treatment, it arises as the breach of an anterior duty of due care, comparable in legal obligation to the duty of due care in carrying out the particular treatment to which the patient has consented. It is not a test of the validity of the consent.