Speed limiters are now mandatory for most large commercial motor vehicles operating in Ontario, regardless of their home province or state. The new Highway Traffic Act requirement applies to commercial vehicles manufactured after January 1, 1995 with a manufacturer’s gross vehicle weight rating over 11,794 kg. Vehicles manufactured prior to this date, as well as buses, cranes and emergency vehicles, are exempt.

The speed limiter must be set to a maximum of 105 km/hr (65 mph) through the ECM (Electronic Control Module). Trucks travelling 115 km/hr (71.5 mph) or above will be automatically charged for not having an activated speed limiter.

While the new law came into force on January 1, 2009, full enforcement did not begin until July 1, 2009. The six-month period was to provide time for industry education and to allow carriers to arrange for the vehicle limiter to be set during the normal course of maintenance.

The Ministry of Transportation expects the speed limiter, which works by limiting the amount of fuel a fuel injector dispenses into the engine when the vehicle reaches a pre-determined speed, to reduce greenhouse emissions and improve road safety.

Section 68.1 of the Highway Traffic Act creates the offence of driving or permitting the operation of a commercial vehicle that is not equipped with a speed limiting system. Deactivating or modifying the speed-limiting system or carrying a device designed to disguise the fact that the vehicle is not equipped with a speed limiter will also be offences.

The law will be enforced by both police officers and Ministry of Transportation officers, with fines ranging from $250 to $20,000. Enforcement officers will plug a small portable device into the connection at the ECM to ensure compliance. Drivers and/or operators will be charged for non-compliance, but non-compliance will not count against CVOR (Commercial Vehicle Operator's Registration) records, as only Ontario and Québec currently require the use of speed limiters. While it is an offence to tamper with the limiter, operators can purchase software/computers that will enable the limiter to be adjusted for operation in jurisdictions with higher speed limits.

The province’s trucking industry’s association (Ontario Trucking Association) was the first to propose the idea of mandating the activation of speed limiters on heavy trucks. Teamsters Canada, on the other hand, which represents thousands of truck drivers across Canada, contends that the legislation will not prevent accidents, but instead will create dangerous road conditions, with trucks being regulated at 105 km/hr and cars traveling at 120 km/hr and faster.