What is the standard of perfection for a doctor?

A physician is not held to a standard of perfection nor does the law require that he or she be a guarantor that the treatment given will be successful. The court in Cardin v. City of Montreal (1961), 1961 CanLII 77 (SCC), 29 D.L.R. (2d) 492 (S.C.C.), at page 494, states: ... Certainly, doctors should not be held responsible for unforeseeable accidents which may occur in the normal course of the exercise of their profession. Cases necessarily occur in which, in spite of exercising the greatest caution, accidents supervene and for which nobody can be held responsible. The doctor is not a guarantor of the operation which he performs or the attention he gives. If he displays normal knowledge, if he gives the medical care which a competent doctor would give under identical conditions, if he prepares his patient before operation according to the rules of the art, it is difficult to sue him in damages, if by chance an accident occurs. Perfection is a standard required by law no more for a doctor than for other professional men, lawyers, engineers, architects, etc. Accidents, imponderables, what is foreseeable and what is not, must necessarily be taken into account.