What is the test for negligence in medical malpractice?

Negligence standards of care are to be measured by the behaviour that a relevant prudent person would undertake, rather than the results that prudent person would seek to attain or avoid. Gonthier J. affirmed this general imperative in an instructive Quebec civil law medical malpractice case, St-Jean v. Mercier, 2002 SCC 15, [2002] 1 S.C.R. 491, at para. 53: The correct inquiry to be made in assessing whether a professional committed a fault is indeed to ask whether the defendant behaved as would a reasonably prudent and diligent fellow professional in the same circumstances. To ask, as the principal question in the general inquiry, whether a specific positive act or an instance of omission constitutes a fault is to collapse the inquiry and may confuse the issue. What must be asked is whether that act or omission would be acceptable behaviour for a reasonably prudent and diligent professional in the same circumstances. The erroneous approach runs the risk of focussing on the result rather than the means. Professionals have an obligation of means, not an obligation of result. [Citations omitted; emphasis in original.]