What is the test for a flexible approach to causation in medical negligence cases?

Snell v. Farrell (1991) 1990 CanLII 70 (SCC), 72 D.L.R. (4th) 289 S.C.C., is the leading case on the issue of causation, and is used as the hallmark for a flexible approach to causation in medical negligence cases. Mr. Justice Sopinka promoted the use of a robust and pragmatic approach to the facts of the case to enable an inference to be drawn even if the conclusion could not be reached on the basis of medical expertise. He stated: It is not speculation but the application of common sense to draw such an inference where the circumstances other than a positive medical opinion permit.