12/13   I just watched Donnie Brasco and got to thinking after the
        scene where Donnie Brasco, still under cover, runs into
        some federal DA or attorney or something, and he beats the
        guy up to prevent the DA from recognizing him (and thus
        revealing his true identity). Does anyone know of what the
        policy is in real life, to prevent potentially serious
        predicaments like this from happening? Is no one allowed
        to acknowledge each other when not in the office?