How is fault determined in a negligence lawsuit after a car accident in Ontario?

Fault after a car accident is assessed using the same basic negligence framework used in any other injury claim: did the driver owe a duty of care to other road users (which drivers generally always do), did their conduct fall below what a reasonably careful driver would have done in the same circumstances, and did that failure actually cause the collision and resulting injury. Evidence like police reports, witness statements, dashcam or security camera footage, road and weather conditions, and the pattern of vehicle damage is typically used to reconstruct what happened and assess whose conduct fell short.

Where more than one driver contributed to causing the collision, fault does not have to be assigned entirely to just one party - the Negligence Act allows fault to be split between drivers based on how much each person's conduct departed from reasonable driving and contributed to the crash. It is also worth knowing that a separate insurance-based process governs certain accident benefits and claims in Ontario, running alongside the negligence lawsuit itself, so a motor vehicle injury claim often involves two related but distinct tracks proceeding at the same time.