Drunk Driver: Dial 911

While driving down the highway in California recently, (read: being driven down the highway) I noticed signs along the side of the road reading:

DRUNK DRIVER
DIAL 911

I was confused. Is this like a college public safety policy, where if you are drunk, and you call the cops, you don't get in trouble?

"Well son, your BAC is .43, and, frankly, I'm shocked you are still breathing, much less able to operate a motor vehicle in any capacity, but, since you called us... we aren't going to arrest you. We are just very dissapointed in you, and will be notifying your parents. Well, move along!"