Few would argue that the driver of a vehicle whose negligence injures another should not be held liable for their conduct, but more contentious are the circumstances in which a vehicle’s owner should be held liable simply by virtue of their ownership. On August 20, in Mustafi v All-Pitch Roofing Ltd, the Alberta Court of Appeal provided new guidance in this area.

Marc Carroll was an employee of All-Pitch Roofing, who had the misfortune to be working on Christmas Eve. Carroll had access to his employer’s truck, which was parked at a construction site, so that he could get tools and supplies out of an attached trailer. Carroll was given the keys to the truck to get warm during his breaks; however, his employer not only told him that he was not allowed to drive it but also warned him that if he moved the truck it would be considered stolen. Under no circumstances would Carroll have been allowed to drive the truck. As it happened, during the day Carroll removed the trailer, drove the truck for a personal errand, and was involved in an accident. He and his employer were then sued.


When dealing with claims against a vehicle’s owner, merely giving possession of the vehicle to the at fault driver is sufficient to engage the Traffic Safety Act’s vicarious liability provisions.

As Carroll did not have insurance, the issue before the Court was whether the employer, as the truck’s owner, was liable for Carroll’s negligence under section 187(2) of the Traffic Safety Act. That section makes the owner of a vehicle vicariously liable for the negligence of a driver who at the time of an accident

a) was driving the motor vehicle, and

b) was in possession of the motor vehicle with the consent, expressed or implied, of the owner of the motor vehicle.

Carroll’s employer had consented to his possession of the truck at the time of the accident, but clearly had not consented to his driving it.

The Law Before Mustafi

The law in Alberta was previously outlined in the Court of Appeal’s 2004 decision in Mugford v Kodiak Construction Ltd (a case decided under the provisions of the now repealed Highway Traffic Act), and Mustafi was argued on the assumption that Mugford remained the law.

Mugford held that a vehicle’s owner is vicariously liable for a driver “who is driving the motor vehicle and who is in possession of it with the consent, express or implied, of the owner”. In other words, the owner had to consent to both possessing the vehicle and driving the vehicle. In addition, the Court held that consent cannot be conditional.

Mugford was a public-policy driven decision, as the Court confirmed that imposing vicarious liability on vehicle owners, who are legally obliged to carry liability insurance, protects the public by providing access to insurance coverage and holding owners responsible for those to whom they lend their vehicles. This follows, as only the owner can determine whether a potential driver is reliable and responsible before handing over the keys.

The Mustafi Decision

In light of Mugford, Carroll’s employer argued that it was not vicariously liable because while they consented to his possessing the truck, they did not consent to his driving. In contrast, the majority of the Court confirmed that the policy considerations that underpinned Mugford remain sound, and even warrant an enlargement. As the current Traffic Safety Act imposes a consent requirement on the possession of the vehicle, and not on the act of driving the vehicle, Justice Macleod (sitting ex officio) for the majority observed:

It is my view that the philosophy of Mugford must be adapted to the legislative change that the only required consent is for possession. Accordingly, it is inappropriate in this case to enforce as against the injured Plaintiff the conditions imposed on possession for the purpose of section 187. To so interpret section 187 is contrary to its remedial object and would not give effect to its purposes as set out by this Court in Mugford.

The issue here is whether or not All-Pitch, having given possession of its vehicle to an employee, can enforce conditions of that possession as against innocent third party victims. In my view, on these facts, the answer is no.

In a strongly worded dissent, Justice O’Brien would have dismissed the appeal on the basis that at the time of the accident (a requirement included in the legislation) Carroll’s possession of the vehicle “was wrongful and without consent” – falling within an exception recognized in Mugford. Justice O’Brien concluded that while policy considerations might favour imposing liability in circumstances such as were before him, “any such alteration of risk would require amendment of the [Traffic Safety Act]”.

Accordingly, absent an appeal the law in Alberta is now that for the owner of a vehicle to be vicariously liable for the driver’s negligence all that is required is that the owner have consented to the driver being in possession of the vehicle. In addition, there is no change to the principle that consent cannot be conditional, which means that agreements such as “you can only drive the vehicle for work purposes” or “you cannot drink and drive the vehicle” will not restrict an owner’s vicarious liability.