up here, we have some interesting laws, like the province I used to live in, allows green lights on personal vehicles operated by volunteer firefighters trying to get to a fire, but only with approval of their town hall, also, herses have purple strobes (one round one on the roof) to be used in a funeral precession, all cars following use 4 ways, and is the only exception that I know of to what SVT just posted, the purple strobe precession has the highest priority of any traffic on the road, if the lead car goes through a light, all other cars go through, they HAVE right of way over police, fire and ems, the only thing they have to stop for is a train, because the train isn't going to stop...
as for the police with their lights on, regular rules of the road apply as for mva's and who's at fault! I think the green lights are allowed out here, I saw one truck last weekend in a more rural area covered in them, with SAR down the side