Motor Vehicle Accidents

How is Fault Determined After an Accident?

Justin Macfayden, JD
Law and Claims Analyst

Fault determination may be legislated, such as Ontario, use industry standards or general agreements, or simply follow best practices based off court precedents and adjuster experience. For example, Ontario Statue RRO 1990 Reg 668 lays out many fault rules and includes diagrams of common collision circumstances that are  helpful in determining fault after an accident.

If the insured disagrees with the fault determination made, they may request that the insurer specify the fault rules used in determining fault, and they may appeal the decision by contacting the company’s complaint officer or ombudsmen. Generally, each province has their own ombudsmen, who may fall under the provincial superintendent.

Despite popular belief, being convicted or charged of a criminal offence does not necessarily mean that a driver is at fault for an incident. This is important to know for the purposes of determining liability under an insurance policy.  

Did you or someone you know get into a car accident? You can determine who is at fault for free through our automated liability calculator.

How is fault determined after an accident? 

After an accident, fault will likely be attributed to each part on a scale from 0% to 100% where 100% is completely liable for the accident and 0% is not liable at all. In many instances, compensation is reduced by the percentage each party is liable for the accident. Also note that if one driver was driver erratically, or unreasonably, they may be held somewhat liable, where they otherwise wouldn't had they been driving safer. This is called contributory negligence.

Jurisdictional Differences

At fault rules vary from province to province based on a variety of variables, including:

  • No-fault legislation
  • Common law vs. Civil code


No-fault insurance doesn't mean insurance companies don't investigate and determine who is at fault following a collision; Ontario law requires to assign responsibility to each motorist involved in the accident. No-fault insurance system means your insurance provider will process your claim and pay for repairs to your vehicle, regardless of who was at fault.

The following provinces have a no-fault or partial no-fault system:

  • Manitoba (closed market – MPI; note: can sue at-fault driver for property losses + deductible)
  • Ontario (open market)
  • Quebec (closed market - Regime d’Assurance Automobile du Québec)

The following provinces are currently tort-based systems:

  • Alberta (open market) Newfoundland and Labrador (open market) – at fault but with DCPD (direct compensation for property damage)
  • New Brunswick (open market)
  • Nova Scotia (open market) - at fault with DCPD and no-fault minor injury coverage
  • PEI (open market)


Some provinces have legislated rules or agreed upon unofficial rules. These rules are in place based on the jurisdiction of the accident, not the jurisdiction of the insured (i.e., an Alberta driver who is involved in an accident in Ontario will be deemed a fault percentage based on Ontario rules, not Alberta rules).  

Determining fault in BC

In BC, automobile insurance is available exclusively through ICBC (the Insurance Company of British Columbia). If responsibility for a crash cannot be determined, then it is considered 50/50. Generally, the ICBC uses crash examples as guidelines for determining fault and disputes are resolved following ICBC guidelines.

In the case of rear-ending accidents, BC differs from the general calculator in that the rearmost driver (whose actions cause the accident) is 100% at fault for all damage, even if the vehicle they strike in turn is pushed into another vehicle.

Determining fault in Alberta

Effective Jan. 1, 2022, Alberta implemented Direct compensation for Property Damage Regulation (DCPD). DCPD will only cover the damage for which a driver is not at fault. These charts and pictures explain specific situations, and might help determine fault in your case.  

If a driver is at fault, they would claim from their own collision coverage for damage to their own vehicle to the extent they are at fault.

Determining fault in Saskatchewan

The information provided by everyone involved in the incident is looked upon to determine the responsibility of the collision. This information includes: the actions of the drivers with respect to the rules of the road, witness reviews, police reports, bylaws, any other governing legislation, and court precedents.

Determining fault in Manitoba

In 1993, Manitoba followed Quebec’s lead and became the second jurisdiction in North America to abolish the traditional tort system and adopt a pure no-fault compensation plan for victims of automobile accidents. The no-fault insurance plan, which MPI has named the Personal Injury Protection Plan (PIPP) came into force on March 1, 1994. Under Manitoba law, you and another motorist involved in a collision can sue each other for the deductible and liability if applicable.  

Determining fault in Ontario

Ontario’s fault determination rules are laid out in statute: R.R.O. 1990, Reg. 668: FAULT DETERMINATION RULES (

Of note in Ontario, in the case of rear-ending accidents involving three vehicles, and the two frontmost vehicles are not moving, the rearmost vehicle is 100% at fault. However, if all three are in motion, the liability is divided equally.

Determining fault in Quebec

All Quebecers are covered by Quebec’s public automobile insurance plan. This plan provides compensation in the event of injury or death as a result of an accident that occurred in Quebec or anywhere else in the world.  One of the founding principles of Quebec’s insurance plan is no-fault coverage for everyone, regardless of who is responsible for a given incident.  Responsibility for an accident is determined by the insurer using, as a guide, the DCA. The DCA (Direct Compensation Agreement)outlines most possible scenarios, and the percentage of responsibility of each driver.  

Determining fault in Newfoundland & Labrador

Newfoundland and Labrador are considered to offer the least amount of accident benefits to its residents, as insureds are required to purchase additional coverage for most benefits. NEWFOUNDLAND AND LABRADOR REGULATION 57/19 (

Determining fault in Nova Scotia

Fault determination regulations are made under Section 138B of the Insurance Act R.S.N.S. 1989, c. 231

An insurer must determine the degree of fault of an insured for loss or damage arising directly or indirectly from the use or operation of an automobile in accordance with these regulations. Nova Scotia uses a No-Fault insurance system. This means that your insurance company will pay for vehicle damage no matter who was at fault. They and the other driver’s insurance company may still determine the at-fault driver after paying your vehicle damage claim.

Determining fault in New Brunswick  

Fault determination rules are laid out in New Brunswick Regulation 2004-141 under the Insurance Act (Oc.2004-532). If you own an automobile in New Brunswick, it’s mandatory under  the law that you have automobile insurance. There is a provision for DCPD (Direct Compensation for Property Damage) which says that even if someone else causes the damage, you will collect compensation directly from your own insurer. There are also accident benefits available for compensation beyond property damage.

Determining fault in Prince Edward Island

Under the Automobile Insurance Fault Determination Regulation (Insurance Act Chapter 1-4), an insurer shall determine the degree of fault of an insured for loss or damage arising directly or indirectly from the use or operation of an automobile in accordance with the regulations. The regulation includes diagrams of collision accidents to help determine fault.

Fault will be determined fault by ordinary rules of law (instead of the regulations) if both of the following are true:

  1. The driver of automobile A involved in the accident is charged with a driving offence AND
  1. The driver of automobile B is wholly or partly at fault, as otherwise determined under these regulations, for the incident.

Determining fault in Northwest Territories

In the Northwest Territories, the determination as to whether a person is legally entitled to recover damages and, in what amount, will be determined either by agreement, arbitration, or the appropriate provincial court.

Determining fault in Nunavut

In Nunavut, all car insurance policies have mandatory provisions dealing with treatment costs under Section B of each jurisdiction’s standard automobile policy. These provisions are known as Section B benefits, and they are based on a no-fault concept. Section B Accident Benefits cover medical recovery and treatment for injuries caused by motor vehicle accident, regardless of whose fault the accident was. Each driver claims these through their own insurer in the event of an accident.

The determination as to whether a person is legally entitled to recover damages and, in what amount, will be determined either by agreement, arbitration, or the appropriate provincial court.  

Determining fault in Yukon

Except from some limited no-fault accident benefits, the Yukon has a fault-based automobile insurance system that is administered by private companies. At fault drivers are liable for the injuries and damages that they cause.  If the insurers cannot settle the matter themselves, either party can sue the other for the remaining damages in court.

The determination as to whether a person is legally entitled to recover damages and, in what amount, will be determined either by agreement, arbitration, or the appropriate provincial court.  

Some Rules of Thumb

As noted above, there are different rules between different provinces. That said, there are some rules of thumb that work for determining liability in most situations.

Backing Up

Whenever a driver is backing up, whether out of a driveway or parking spot, they are usually 100% at-fault. However, note that parking lot collisions generally are 50/50.

Entering a Roadway

When a vehicle is entering a roadway, either from a private roadway or a parking spot, and they strike another vehicle already on that roadway, they are usually 100% at-fault. Similarly, if a vehicle strikes another while merging onto a roadway or joining a roadway from another controlled access roadway, they are usually 100% at-fault.

Rear End Collisions

When a driver read ends another vehicle, they are usually 100% at-fault. However, if a vehicle performs an erratic manoeuvre that leads to them being hit from behind, they may share in liability (contributory negligence)

Multiple Vehicle Collisions

In a multi-vehicle collision, fault gets more complicated. If you are rear ended and that causes your vehicle to rear end another vehicle, you will share some fault for damage to the vehicle in front of you, often 50/50 with the vehicle that hit you. This usually carries forward for each subsequent rear-ending and the math gets complicated. Often times, insurance companies will simply agree that every driver is 50% at fault rather than performing the calculations.  

Open car doors.  

If you leave your door ajar, regardless of the reason, and another car knocks it off its hinges while driving by, you’re usually 100% responsible for the accident.


While performing a U-turn, the driver making the turn is usually 100% at fault for any accident that arises as a result.

Sideswiping and Oncoming Traffic

While travelling in the same direction, in different lanes, both drivers are generally deemed 50% at fault if both or neither initiates a lane change and the vehicles strike at or near the centre line between their lanes. If only one vehicle makes a lane change, they are 100% at fault.

While travelling in opposite directions, both vehicles are usually deemed 50% at fault unless one vehicle is well over the centre line and in the lane of the oncoming vehicle, in which case they are usually 100% at fault. Similarly, if an oncoming vehicle initiates a left turn into the path of a vehicle at a controlled intersection (lights or signage), the turning vehicle is usually 100% at fault. At uncontrolled intersections:

  • If one vehicle enters before the other, the first vehicle to enter the intersection is often 0% at fault.  
  • If both vehicles enter at the same time, then the vehicle to the right is often 0% at fault.

These rules are superseded if either vehicle fails to obey signage or lights at a controlled intersection, in which case the driver failing to do so is often 100% at fault. If both are not obeying signage, or it cannot be determined who did or did not obey signage, they are generally each 50% at fault.

Parked Vehicles

If a legally parked vehicle is hit by another vehicle, the driver of the parked vehicle is usually 0% at fault. If a vehicle is illegally parked, that driver is likely 100% at fault.

Still unsure of how to proceed? 

If you've been in an accident, contact your insurer, or the insurer of the party you believe is responsible for the accident. If you are still unable to resolve the liability issue, contact the superintendent of insurance for your province, or the province the incident took place. If your issue is still unresolved, contact your local insurance attorney or personal injury attorney. You can also determine who is at fault for free through our automated fault system.

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