If a radar detector is basically a radio, how can it be illegal?

How can it be against the law to detect a naturally occuring phenomenon? That’s the question your mind bumps up against when you think about buying a radar detector. Of course, you’re thinking of buying one, not because you as a law-abiding citizen are going to speed, right? You’re buying a radar detector because as a fond adherent to constitutional law, you consider the use of radar detectors to be warrantless search and seizure and you’re just keeping this police on alert. That’s the reason, right?

What is a radar detector anyway?

Putting aside all of that, a radar detector really is just a fancy radio that tunes to the frequencies used by police radar guns. Some have a few more features than that but it’s basically a radio that makes a noise when it detects radio waves over a certain level. That doesn’t sound like it should be illegal.

How can there be a law against that?

However, many states and provinces have laws that say in effect, “if there’s a thing and it has no other purpose than to make it easy to break the law, then having it is illegal. This applies to things like untraceable poisons, drug paraphernalia, links to sites with inappropriate pictures of minors, that stuff. And, radar detectors.

What a radar detector does is listen for a frequency that’s only used by law enforcement. That frequency isn’t used for civilians and nothing on the planet puts out strong radio waves at that frequency. So if you have a radar detector, the reasoning is that the only thing you would use it for is listening for law enforcement radar guns, and the only reason you would do that is so you could speed. It’s a pretty big leap, and at some point it’s probably going to go to the Supreme Court, but for now that’s the argument that some states use to make it illegal to own a radar detector.

By the way, it’s also illegal to listen in on certain military transmissions. It’s definitely illegal to broadcast on any frequency where you’re not licensed. This applies to things like radar jammers, which are never legal under any circumstances, so let’s not even talk about that any more.

Where can you use a radar detector?

Radar detectors are actually legal in most states and provinces. There’s no overriding federal law (yet) that prevents their use. So, if you do decide to buy a radar detector like this one, you should be fine, unless you’re operating a commercial vehicle. Many states allow radar detectors for personal use but not for commercial use — there’s a very decent list here provided by the AAA and CAA. Of course, what you do with a radar detector is up to you. I’m certainly not advocating going faster than the posted speed limit. That wouldn’t be legal.

Get radar detectors and more from Solid Signal

If you’re looking for the best accessories for your trip away from the house, you’ll find everything you’re looking for, at the best prices and with the best support, when you shop at Solid Signal.

About the Author

Stuart Sweet
Stuart Sweet is the editor-in-chief of The Solid Signal Blog and a "master plumber" at Signal Group, LLC. He is the author of over 8,000 articles and longform tutorials including many posted here. Reach him by clicking on "Contact the Editor" at the bottom of this page.