What is the modified objective test in medical malpractice cases?

In the latter case, Cory J. described the considerations that led the court to adopt the modified objective test in Reibl v. Hughes as well as the precise contours of the test, at paras. 4-6, as follows: Laskin C.J. … rejected the pure subjective approach to causation. He explained at p. 898 that 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. ... Accordingly the subjective test would necessarily cause the trier of fact to place too much weight on inherently unreliable testimony. While an objective test would prevent an inappropriate emphasis being placed on the plaintiff’s testimony, Laskin C.J. thought that a purely objective test also presented problems. At p. 898, he discussed his paramount concern with an approach based on the actions of a hypothetical reasonable person: ... a vexing problem raised by the objective standard is whether causation could ever be established if the surgeon has recommended surgery which is warranted by the patient’s condition…. The objective standard of what a reasonable person in the patient’s position would do would seem to put a premium on the surgeon’s assessment of the relative need for the surgery and on supporting medical evidence of that need. Could it be reasonably refused? In short, the purely objective standard might result in undue emphasis being placed on the medical evidence, essentially resulting in a test which defers completely to medical wisdom. To balance the two problems, Laskin C.J. opted for a modified objective test for causation … 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 the possible risks. [Emphasis in original.]