What is the standard of care of a medical professional?

It is doctrinal tort law that assuming a duty of care is established, a breach of duty is established by the standard of care of the reasonable man or woman. In Ryan v. Victoria (City), 1999 CanLII 706 (SCC), [1999] 1 S.C.R. 201, Justice Major discussed negligence and the standard of care; he stated at para. 28: 28. Conduct is negligent if it creates an objectively unreasonable risk of harm. To avoid liability, a person must exercise the standard of care that would be expected of an ordinary, reasonable and prudent person in the same circumstances. The measure of what is reasonable depends on the facts of each case, including the likelihood of a known or foreseeable harm, the gravity of the harm, and the burden or cost which would be incurred to prevent the injury. In addition, one may look to external indicators of reasonable conduct, such as custom, industry practice and statutory or regulatory standards. Thus, the standard of care of professionals is typically proven by evidence of the behaviour of other professionals to avoid causing foreseeable harm.