It was in LaToya's book and what comes out of her mouth is always questionable. Anyway, the story was that Michael traveled alone with Bill Bray and in Alabama they stopped to pee and while Bill went to the bathroom Michael was looking around in the shop where they stopped. And the next thing Bill hears was Michael screaming and when Bill came running out of the bathroom Michael was on the floor and this guy was beating and kicking him and shouting racist curses at him. And he didn't realize who he was, he just attacked him because he was black. Oh, I think he also accused Michael of stealing from the shop. Michael got injuries but he never reported the case to the authorities.
Well, this is according to LaToya, so I don't know how true the story is.
Another story was in Katherine's book from somewhere in the early 80s. Michael was driving his Rolls alone and a policeman stopped him and he didn't want to believe the car was his, he thought he stole it (because he was black) and he put Michael in jail for a couple of hours until his family came for him and cleared the matter. Michael enjoyed being in a jail for a couple of hours because he always wanted to know what it's like from the inside, so he took it lightly, according to Katherine.