Like most Mafia "rules," there's no such "rule" about killing a Don. Supposedly, a guy who wants to kill a Don needs the Commission's approval. As a practical matter, he shoots first, mends fences later. Gotti never asked the Commission's approval to kill Castellano. But after the shooting, he was seen shmoozing Dons and capos from other families, who were relieved to see Castellano dead. Albert Anastasia didn't ask anyone's permission to make his boss, Vincent Magano, disappear. Vito Genovese didn't ask anyone's permission to have Anastasia killed, though he did call the famous Apalachin meeting in part to anoint Carlo Gambino as Anastasia's predecessor.