Is It Really Legal To Install a Yellow Flashing Light on Your Truck’s Roof?

The lights you can legally install on the roof of your pickup trucks depend on the laws in your state. That said, laws around flashing yellow lights are much more permissive than laws governing red and blue lights. This is why you see yellow warning lights on many civilian vehicles, such as plow trucks and tow trucks.

Are emergency lights federally regulated?

There is actually no federal law regulating emergency lights. Each state gets to make its own guidelines for police, fire trucks, and civilians to interpret. This is why in some states, police use blue lights while in other states, police use red.