What is the test for determining whether a person is injured in a motor vehicle accident?

The classic statement of the law of causation by Mr. Justice Sopinka in Snell v. Farrell, 1990 CanLII 70 (SCC), [1990] 2 S.C.R. 311 328 is that causation need not be determined by scientific precision. It is a practical question of fact that can be answered by ordinary common sense.

Once factual causation is found, liability may still be limited in the assessment of damages. I note the well-established principle of tort law that the defendant need not place the plaintiff in a better position than his original position and should not compensate the plaintiff for damage he would have suffered in any event, otherwise known as the crumbling skull rule: Blackwater v. Plint, 2005 SCC 58 at paras. 78 - 81.