Here is a list of states where radar detectors are illegal:

• Virginia
• Mississippi

In addition, the District of Columbia does not allow radar detectors either.

It is worth noting that radar detectors are prohibited in all commercial vehicles weighing over 10,000 lbs, no matter what state you’re driving in. In commercial vehicles under 10,000 lbs, radar detectors are allowed in all states except for Illinois, Iowa, Minnesota, New Jersey, New York, Virginia, and Washington D.C. .

It is important to follow the laws of the state you are driving in to avoid fines and other penalties.