You already know texting while driving is ridiculously dangerous, and in many place even illegal, but the cops can’t enforce what they can’t see, right? Not so fast.

If you think you can get away with a quick message to your friend while cruising to get your morning coffee, you might end up with a ticket thanks to a new type of sensor gun.

When a cell phone is being used, it emits radio frequencies that can be picked up and detected. The frequency varies depending on what the phone is being used for—data, voice calling and, of course, texting—which can give a person away if they happen to be secretly tapping away at their phone out of view of any passersby.

A company in Virginia called ComSonics wants to turn this type of sensor into a pointable device that could be used by law enforcement in the same way a radar gun is. If an officer could target your vehicle with the device and detect a texting signal, they might be able to pull you over without ever actually seeing the violation take place.

Privacy hawks take note: The device would only be able to sense that a phone is being used for a specific purpose, and it cannot record or translate that signal into something readable. It’s simply designed to detect.

Of course, proving that a text was being typed out by the driver could be difficult to pull off, especially if a vehicle contains multiple occupants who could be texting. However, if a texting frequency is beaming from your car and you’re the only one in it, that’s going to be pretty hard to explain to an officer.

The device itself is reportedly nearing production, but would need to be tested and adopted by law enforcement agencies and approved by any state or local governments before it is put to use.