I'd be very circumspect about intervening in an unknown situation. I'm not saying I wouldn't, but you assume all risk and have much less legal protection under those circumstances. Is that a thug assaulting a woman in the parking lot? Or an undercover officer effecting an arrest on a wanted felon? What if you intervene and wind up injuring an innocent party or bystander?
These are all things to consider before jumping into the fray.
These are all things to consider before jumping into the fray.