This is purely hypothetical, it has never happened to me or anyone I know. Say, you're driving down the freeway. You're chugging along at 70mph and traffic is mild, but not bad. In your rear-view mirror, you see some idiot cutting in and out of traffic. He's cutting people off and when he has any little stretch of road, he guns it, going upwards of what maybe 90mph. He blatantly cuts you off and whizzes down the road. As you're fuming and swearing at this idiot, he tries to take an offramp at too fast of a speed, goes off the offramp and his car rolls in a ditch a few times. There's a huge plume of dust and smoke and it looks kind of bad. The question is: Are you going to be a good Samaritan and call 911 to get help for this guy? Or do you think that he deserves it and just drive on past (knowing that maybe some other person will call 911)?