As of March 2015, radar detectors are illegal in Virginia and the District of Columbia, according to The Law Offices of Lee B. Steinberg, PC. Drivers can receive tickets for having these devices in vehicles, and law enforcement officers in these locations may confiscate radar detectors.
Some law enforcement agencies have devices that detect small frequencies used in radar detectors, says the law office. Some states prohibit radar detectors on the outside of vehicles. Federal law bans radar jammers, which are devices that interfere with police radar. Radar detectors are illegal on U.S. military installations. Laser jammers, devices that interfere with laser-type speed detectors, are banned in 10 states and Washington, D.C.
Radar detectors are also illegal in most Canadian provinces, while radar detectors in American commercial vehicles have been banned since 1995, notes Escort Radar. A commercial vehicle means a single vehicle weighing more than 10,000 pounds or a gross combination weight of more than 26,000 pounds, including trailers and towed units. Radar detectors are illegal on vehicles designed to carry 16 or more passengers, including the driver. Any vehicle, regardless of size, carrying hazardous materials cannot have a radar detector. A gross weight rating means the total weight of a vehicle, including the load, as specified by the manufacturer of the commercial vehicle.