I can tell you this much... Any policeman out there is required to follow the rules of the road EXACTLY as we are, except in response to an emergency. These 2 rules apply, when they ARE responding to an emergency:
(a) If the vehicle is being driven in response to an emergency call or while engaged in rescue operations or is being used in the immediate pursuit of an actual or suspected violator of the law or is responding to, but not returning from, a fire alarm, except that fire department vehicles are exempt whether directly responding to an emergency call or operated from one place to another as rendered desirable or necessary by reason of an emergency call and operated to the scene of the emergency or operated from one fire station to another or to some other location by reason of the emergency call.
(b) If the driver of the vehicle sounds a siren as may be reasonably necessary and the vehicle displays a lighted red lamp visible from the front as a warning to other drivers and pedestrians.
They MUST use both lights AND siren when they are going to break any rules of the road and when breaking said rules, must still use due regard for the safety of all other drivers and pedestrians.
This is in accordance with the CVC. California Vehicle Code section 21055.
Since I am an MP in CA. I have to be familiar with this stuff...