"• Under federal law, the use of radar or laser speed detectors is illegal in all commercial vehicles over 10,000 pounds.

• Radar detectors are illegal to use in any vehicle in the District of Columbia.

• Radar detectors are illegal to use in any vehicle in the state of Virginia.

• Radar detectors are illegal to use in any vehicle while on any military installation."

https://k40.com/are-radar-detectors-illegal/