What is the test for expert testimony in medical malpractice cases?

In Reid v. Livingstone, [2004] O.J. No. 1477 (S.C.), Cameron J. at para. 12, affirmed a number of court decisions on the significance of expert evidence: In order to establish whether the conduct of a person engaged in a technical occupation not within the expertise of the ordinary person, such as a doctor or nurse, met the standard of care required of them, or those for whom they are responsible, the plaintiff must provide evidence of a person qualified and experienced in the field of the conduct at issue that the defendants' conduct in the circumstances failed to meet the standard of care the defendant owed to the plaintiff.