Ryder Truck Rental Canada had been charged after the dual wheels, hub and axle separated as a unit from one of its trucks in July 1997. Two lower courts said an Ontario law imposing stiff fines for lost wheels should not apply because the wheels themselves did not separate from the axle.
The Ontario Court of Appeal decision upheld the earlier rulings.
Transport ministry lawyers argued the so-called "flying wheel" law should apply if a vehicle assembly that includes a wheel were to separate from the vehicle. The court said this interpretation is too broad, noting that an operator who lost an entire trailer could be convicted.
A more appropriate charge against Ryder would have involved operating dangerous or unsafe vehicles on highways, the court said, although the judges acknowledged that the vehicle had passed a provincial inspection the day prior to the mishap.
Section 84.1, enacted in 1997 as the Wheel Safety Act, imposes fines of between $2,000 and $50,000 (Canadian) without the benefit of a due-diligence defense by the vehicle owner or operator should a wheel become detached from the vehicle.
Last year, a Sudbury lower court judge ruled that the law's absolute liability provision was unconstitutional because it punishes the vehicle's operator regardless of who is at fault.