What is the test for finding both parties to be partially at fault in a motor vehicle accident?

Having found both parties to be partially at fault, Sewell J. went on to deal with the matter of apportionment of liability. In doing so, he applied the principle that: Where a plaintiff pedestrian and defendant driver both fail to meet the requisite standard of care and an accident ensues, the court may apportion liability between them. Before liability will be apportioned, however, the defendant must establish that the plaintiff’s fault was a proximate, or effective, cause of the loss: McLaughlin v. Long, 1927 CanLII 53 (SCC), [1927] S.C.R. 303.