Would she not even be prosecuted for careless driving, having sped round the corner, lost control and hit a stationary car head on in front of two police officers?
(Incidentally, I can say with certainty that I've never drunk driven after a big night out, as I virtually didn't drive at all until DS was born and have only had one big night out since then, which was a Friday and I didn't drive until the Monday. And come to think of it, I am now too old to have big nights out if I intend to do anything the next day.)
alittleone -- I would be very inclined to take the least scary of the coven aside and point out that the accident happened right in front of two police officers, that you were directly behind the woman who was hit so that if she was on the wrong side of the road, so was the entire queue of traffic, and ask in concern tone of voice if she's heard how X's blood test at the police station turned out because you were concerned for her licence when she failed the breathalyser test. Or possibly drip-feed those one at a time.