Who’s at Fault in a Multi-Vehicle Collision?

Posted by Injury Lawyers of Ontario on February 04, 2021

In August 2019, there was a multi-vehicle crash involving eight vehicles travelling east-bound on the QEW near Trafalgar Road in Oakville.  In addition to relatively minor injuries to seven passengers, the accident resulted in the death of a 34-year-old Niagara Falls woman whose car became pinned to a concrete barrier by a tractor trailer truck. The driver of the truck, a Mississauga man, was charged with criminal negligence causing death and dangerous operation of a motor vehicle causing death, in connection with the crash.

Every year, in Toronto and the GTA, there are many multi-vehicle car accdents that result in devastating consequences for some of the vehicle occupants.  Multi-vehicle collisions are increasingly common in Ontario and due to the prevalence of transport trucks on our highways, many of these collisions involve tractor trailer trucks, which increases the likelihood that passengers in smaller vehicles will incur catastrophic injuries in the event of a crash.  

How do we decide who’s legally at fault in multi-car crashes?

The Ontario government has defined rules under the Insurance Act for determining who is at fault in a multi-vehicle crash and these rules apply even when no driving-related criminal charges were applied against a particular driver (see fault determination rules).

The fault determination rules will be applied by insurance companies when deciding whether or not your insurance rates will be increased, and also in personal injury lawsuits arising from a multi-vehicle crash.

Before looking at rules that apply to crashes involving several vehicles, it must be noted that there is a general rule that is applied to all rear-end collisions involving 2 or more vehicles.  And that is, that the onus is always on the rear driver to be watchful and leave enough distance between their vehicle and the vehicle in front, so that they have enough time to avoid a crash if the vehicle ahead of them unexpectedly slows down or stops. 

The degree of fault between any two vehicles involved in the crash is determined without referring to collisions involving other vehicles or either of the two vehicles.

In the following first 2 scenarios, we’ll assume that there are three vehicles travelling in the same lane involved in a rear-end collision (the first (A), middle (B) and last (C)).

1)  When all of the vehicles were in motion:

  • In the collision between vehicles A and B:
    • The first vehicle (A) is not at fault.  
    • Vehicle B is 50 per cent at fault.
  • In the collision between vehicles B and C:
    • Vehicle B is not at fault.
    • Vehicle C is 100 per cent at fault.

2) If only the last vehicle (C) was in motion when the crash occurred:

  • In the collision between vehicles A and B:
    • Neither vehicle A or B is at fault.
  • In the collision between vehicles B and C:
    • Vehicle B is not at fault.
    • Vehicle C is 100 per cent at fault.

3) In a multi-car pileup involving three or more vehicles travelling in adjacent lanes and in the same direction, there is a general rule  (although this does not form part of the law):

  • For each collision between 2 vehicles that are involved in the pileup, drivers of each vehicle are generally found 50 per cent responsible.

State Farm Mutual Automobile Insurance Company v. Old Republic Insurance Company of Canada is an insurance dispute that arose when multiple cars were involved in a Mississauga accident. The accident occurred when a heavy bottling truck (vehicle C) struck a car (vehicle B) which was stopped at the time, causing vehicle B to crash into a stopped car in front of it (vehicle A).  And, the judge ruled that the third vehicle (vehicle C) is responsible for the damage to all 3 vehicles involved in a Mississauga collision.  

The trial judge in this case referred to Royal & Sunalliance Insurance Company of Canada v. AXA Insurance (Canada) where the Court held that “the insurer of a vehicle that initiates a chain reaction collision is liable to indemnify all other insurers for the SAB payments flowing from the incident “.  Old Republic, the insurer for the truck, appealed this decision and argued that the decision places the economic viability of Ontario’s no-fault accident benefits system at risk.  However, the Appeal judge upheld the original decision on the finding that the Fault Determination Rules clearly state that the last vehicle is 100 per cent at fault if it is the only vehicle in motion when the incident occurred.

If you were injured in a rear-end collision and are seeking damages for your injuries and losses, talk to a knowledgeable car accident lawyer at Injury Lawyers of Ontario to ensure that you have strong representation against the insurance company and get the compensation you deserve.


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