What is the current state of the law on medical malpractice claims against the medical profession for failure to warn?

In Arndt at 548, the court pointed out that claims against the medical profession based on failure to warn would “inevitably be hypothetical” as they are based on constructing what would have happened if the patient had been fully informed of the risks of a procedure. The court considered the application of the “modified objective” test set out in Reibl v. Hughes,1980 CanLII 23 (SCC), [1980] 2 S.C.R 880 and offered the following instructive comments at 545 - 550: …the plaintiff’s testimony as to what he or she would have done, had the doctor given an adequate warning, is of little value: It could hardly be expected that the patient who is suing would admit that he would have agreed to have the surgery, even knowing all the accompanying risks. His suit would indicate that, having suffered serious disablement because of the surgery, he is convinced that he would not have permitted it if there had been proper disclosure of the risks, balanced by the risks of refusing the surgery. Yet, to apply a subjective test to causation would, correlatively, put a premium on hindsight… In other words, the plaintiff would always testify that the failure to warn was the determining factor in his or her decision to take the harmful course of action. These words are as persuasive today as they were when they were written. The test enunciated relies on a combination of objective and subjective factors in order to determine whether the failure to disclose actually caused the harm of which the plaintiff complains. It requires that the court consider what the reasonable patient in the circumstances of the plaintiff would have done if faced with the same situation. The trier of fact must take into consideration any “particular concerns” of the patient and any “special considerations affecting the particular patient” in determining whether the patient would have refused treatment if given all the information about possible risks. … … Sopinka J. (McLachlin J. concurring) … in Hollis … elaborated upon the advantages of this approach to causation. A subjective approach … fails to take into account the inherent unreliability of the self-serving assertion of a plaintiff. The plaintiff may honestly believe that he would not have consented to a procedure if all the risks were disclosed. However, this is only the plaintiff’s opinion about what he would have done in a situation which never arose. As such, the opinion may be honestly held and given, but rejected by the trier of fact. As Sopinka J. stated at pp. 688-89: In evaluating the opinion, the trier of fact must discount its probity not only by reason of its self-serving nature, but also by reason of fact that it is likely to be coloured by the trauma occasioned by the failed procedure. For this reason, the most reliable approach in determining what would in fact have occurred is to test the plaintiff’s assertion by reference to objective evidence as to what a reasonable person would have done. [Emphasis in original.] … In my view this means that the ‘reasonable person’ who sets the standard for the objective test must be taken to possess the patient’s reasonable beliefs, fears, desires and expectations. Further, the patient’s expectations and concerns will usually be revealed by the questions posed. Certainly, they will indicate the specific concerns of the particular patient at the time consent was given to a proposed course of treatment. …