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Who is at fault when there is a sudden unexpected stop in a rear end accident?

The issue of rear end collisions come up all the time in motor vehicle accident litigation. It is presumed that the car striking the one in front of it is at fault. The Ontario Court of Appeal said as much in a 1932 case called Beaumont v. Ruddy. But is this an absolute rule? No. Like every self-respecting rule, there are exceptions.


Consider the scenario of the sudden and unexpected stop. Imagine that Driver A and Driver B are moving in the same direction at fifty kilometres per hour down an urban street. Driver A is in front. Suddenly, he remembers he left the stove on at home and slams on the brake. Driver B, who is trailing twenty metres or roughly three car lengths back, can see the road ahead. There are no dangers or hazards. No children playing by the side of the road. No cars or motorcycles poised to enter the roadway. In short, there is no reason to anticipate that Driver A will stop suddenly.


Driver B sees the brake lights on Driver A’s car the moment they come on. His vehicle is travelling roughly fourteen metres per second. Since he is thirty metres back he has just a shade over two seconds before his front bumper collides with the rear bumper of Driver A’s car.


Driver B reacts as quickly as he can but the two cars collide.


Is Driver B responsible for this crash. The answer is unequivocally yes. But is he fully responsible? Probably not. The Negligence Act allows the court to split responsibility between the drivers.


How would you split responsibility between these two drivers?


What factors would be important to you?


What if Driver B was elderly and his reaction time was slower than that of a younger person? Wouldn’t we expect him to leave more room?


What if Driver A was operating a van and Driver B couldn’t see the roadway ahead.


What if Driver A was braking for a child that had unexpectedly run onto the road?


What if Driver A was braking for a squirrel?


What if Driver A’s brakelights weren’t working?


A judge and/or jury are at liberty to consider all factors in arriving at a decision regarding who is at-fault for a car accident, but no matter how you spin it, a rear-end collision is almost always the fault of the trailing car.


Practically speaking, the driver who gets rear-ended is in a much more vulnerable position. The individual’s body is pushed forward with the momentum of his vehicle. His head does not move forward at that speed and is left hanging in space. It pivots backward on his neck, hits the headrest and bounces forward. His brain, which is the consistency of gelatin, smashes against the front of his inner skull as his head whips backward and then smashes against the back of his skull as his head whips forward. The bottom of his brain is raked across the bony protuberances that form the inside of the lower skull cavity. The joint capsules surrounding the facets in his neck burst and ligaments stretch and tear. Muscle tissue connecting the individual vertebrae rip and tear. Some of this happens at the microscopic level but can lead to the formation of scar tissue and long-term pain. All of it is bad.


The guy in the trailing car doesn’t get injured to anywhere near the same extent. If the purpose of the law is to protect the vulnerable, then having the trailing driver bear responsibility for rear-end collisions makes sense.


The moral of the story is that we must always leave room for safety. It sounds trite, but it’s true.


So simple. So easy.



Edward Bergeron

Ted Bergeron is a Queen’s University graduate with degrees in Physical Education, Arts, Education and Law.

Ted’s legal career started in insurance defence litigation. He worked at a boutique law firm in Toronto, servicing only insurance companies. He switched to representing only injured clients and their families in 1995. He knows both sides of the system inside and out.

He has lectured extensively in the School of Rehabilitation Therapy, the School of Physical and Health Education and the Faculty of Law at Queen’s University. He has worked in a volunteer capacity with the Law Society of Upper Canada as an instructor in the Bar Admission Course teaching Civil Litigation.

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