How is causation determined in a motor vehicle accident?

The issue of causation is considered after first determining the standard of care and whether it was breached. The onus is on the plaintiff to establish both causation and negligence. Causation is established once the plaintiff proves on a balance of probabilities that the defendant caused or contributed to the injury. Causation is a practical question of fact which can be best answered by ordinary common sense rather than theory. The general but not conclusive test for causation is the “but for” test which requires the plaintiff to show that the injury would not have occurred but for the negligence of the defendant: see Vuong v. Morton, [2009] O.J. No. 4661 (S.C.) at para. 156, appeal dismissed [2010] O.J. No. 4128.