Originally Posted by Richard Cranium
Careful. Here in Ontario Canada radar detectors are in fact illegal to own and if caught it will be confiscated.
In the US they can't do that. It isn't contraband. It is a product legal within the United States. A state legislature can outlaw the usage, but they can't outlaw the sale or possession - that would be a violation of federal commerce laws which establish a common market.
Another interesting example - it is illegal to have a radar detector inside any commercial vehicle in the US. But the Fedex guys have no difficulty delivering them to your home. It illustrates the point, that transporting is not illegal, using is illegal.
In Florida a law was proposed to ban radar detectors in 2007 but died on the Senate floor.