In Colorado, they're illegal. Something to do with only an emergency vehicle is allowed to have a flashing blue light, (I believe).
However, I don't know of a single person that has ever been given a ticket for having them.
Kinda like front. license plates. On older vintage cars, hot/street rods, you're more likely to get away without running a front. plate, even though that's illegal here too.
My personal opinion, and only cause you asked... If you like them get them.
Myself, I can't see them on a 66, or most vehicles with large and/or plastic taillights, but different tastes keep things unique.
