"To intervene or not" is really tough. I have always erred on the side of intervention before, because I wouldn't feel right not doing anything. I think I still stick to that. But something happened a couple weeks ago that gave me pause...
At my workplace, a man started beating his autistic son. Like, right there in front of everyone. I wasn't there at the time, but the people there called the police and prevented him from leaving. But, when the police came, they didn't arrest the man or do ANYTHING -- because our cameras were down, so they couldn't confirm that the beating had happened.
In a situation like that, calling the police will just provoke the abuser, and if the police can't actually arrest them or remove the child, is the abuser going to take that out on the child later?
It definitely made me hesitant about intervening in a situation that I'm physically incapable of changing (like removing a child from a grown man). That said, if I actually walked in on someone raping a child (or beating a child, like my coworkers did), there's no way I would *not* do something. It's just... what if they can't do anything?