i have a few cops that live on my street/next street over. In the past, I came home at same time (3am or so) as this one cop. Frequently. I saw him and I making the same travel almost every weekend.
He would see drunk drivers - I mean obvious drunk drivers all over the road - and he'd drive right past them. He was off-duty obviously, driving home after a long days' work, i'm sure. But there was one time, a drunk almost hit us both - and he just let the drunk A-hole drive away, and he kept on driving home.
I have always wondered what their obligation was, what their power was. He probably had to get up early and the LAST thing he wanted to do was deal with a drunk idiot alone and lose 3 hours booking this obviously drunk a-hole. But what if that drunk travels another block and hits and kills someone?