If I'm not mistaken a cop cannot "legally" violate a motor vehicle law unless it is actually required to complete his duties, or if an emergency. Cutting to the front of line is not required. But, try to get that enforced.
I went down to the Star Spangled celebration over the weekend. As I was crossing the road, and the traffic was stopped at the lights, a motorcycle cop filtered past a couple of cars to the front. I asked him why I couldn't do that on my bike, and he said that I could if I got the lights.
year two back my wife and I were riding through town here at home city cop pulled out in front of me after rolling thru stop sign locked up both front and back brakes stopped just inches from his passenger door calmly put stand down walked around and had few choice words with him with traffic backing up both sides made him call his supervisor and had a few comments what I thought of officer catain told me to leave while I still can
Legal in CA! So awesome. Though they finally put restrictions on it, so that it's not legal to "lane share" at high speeds like a crazy person on the freeway.