I'm in Colorado…. Originally I talked to dozens of officers and state troopers about this project. They said that mock-up lights (a bar painted blue) would technically be legal, but you still run the risk of police impersonation.
You cannot have blue lightbars visible from the FRONT of your vehicle.
Blue, definitely emergency services. llegal.
Red is mostly for official emergency services, but also volunteer firefighters. Illegal.
Purple, funeral/forest fire patrol, though could be confused for blue. Technically legal from all the research I have done. I think amber is more associated with emergencies or hazards with the general public (think tow trucks, snow plows, animal control, garbage trucks, wide-load) than purple, so it is slightly safer..Legal… probably.
Green - emergency command center or chief vehicle. Illegal.
Amber - this is what we use. Originally I talked to dozens of officers and state troopers about this project. They each said that so long as we weren't pulling anyone over or presenting ourselves as law enforcement that we could go nuts and do whatever.
As time went on and we put the lights into practice, our capabilities were narrowed. We could not “flash” the lights on public roads. Then we were told not to run the lights while the car was moving on a city street.
I was recently running the lights while pulling up to a store in a parking lot, I was accosted by an off-duty officer (who happened to be the guy who pulled me over last time for a siren violation), who told us this:
The law is very very specific. It is meant for the ABSOLUTE safety of others. Some old lady might see flashing lights and freak out and pull over for you. Someone could be mad that you are running the lights in front of their store and turn you in. Someone could sue you for police impersonation.
Now, we've never encountered ANY of this, our car does NOT look ANYTHING like a cop car, and we never run the lights if someone is in front of us (as a rule of thumb), and we never ran the lights while travelling at or above the speed limit.
Some cops will understand what you are doing and not care. Others will let you off with a warning. And a very few will uphold your State Laws, laws that were enacted to protect the lowest-common demoninators of our society. You know, the people who need the warning on hair dryers not to use them in the shower. They have to be protected in case they don't understand what you are doing.
So, you can have working lights on your car, but according to the law (at least ours, yours may be very similar), you cannot run the lights unless your car is at rest, and on private land with the owners permission.
The best thing I can recommend is drive around and talk to cops, state patrol, judges, everyone before starting your project. Write down what individual officers say and ask them for their card (business card with name and contact info on it). Keep these along with your states Peace Offical Manual in your car, with all the areas concerning emergency lights bookmarked.
A good rule of thumb is that if the officer has to look it up in order to give you a ticket, how are you expected to know? But after one warning from an officer, all bets are off.
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As for my situation, we've become such local celebrities that I am pursuing a bill or pardon or permit or some sort of authorization to run my lights under the conditions that we put public safety first, and that we have designated areas in town that local law enforcement know about where we can run the lights. The situation is currently very grim, but I'll keep pushing it, even if I have to take it to the state level.
Good luck, keep asking questions.