Guide to Legal Aspects of Radar Detectors

A radar detector is an electronic device used by motorists to determine if their speed is being monitored by a radar unit. In some countries and areas, using or possessing a radar detector is illegal and may result in fines, seizure of the device, or both.

Legal Aspects of Radar Detectors:
United States law varies from state to state, but detectors are generally legal in private vehicles under the Communications Act of 1934[7] and illegal in commercial vehicles by DOT regulation (49 CFR 392.71).

Exceptions:
Illegal in all vehicles: Virginia, Washington D.C., U.S. military bases Illegal in commercial vehicles under state law: Illinois, New York (specifically, commercial vehicles over 10,000 pounds (4,500 kg) and all vehicles over 18,000 pounds (8,200 kg))

Indirectly illegal:
Minnesota and California (illegal to hang anything from the windshield with suction cups; however both dashboard and visor mounting is allowed.) It is also indirectly illegal in NY State, pursuant to Title 3 Article 9 § 375.30 of the New York State vehicle and traffic law.

It states:
“It shall be unlawful for any person to operate a motor vehicle with any object placed or hung in or upon the vehicle, except required or permitted equipment of the vehicle, in such a manner as to obstruct or interfere with the view of the operator through the windshield, or to prevent him from having a clear and full view of the road and condition of traffic behind such vehicle.”