Irish Mafia and Don Sonny got it right. I'll add this:
Charlie Luciano formed the Commission in 1931, after the Castellemmarese War. Its members were the heads of the five NY families and a rotating group of four out-of-town Dons. Luciano formed it because Salvatore Maranzano, the winner of the Castellemmarese War, had declared himself capo di tutti capi over all the NY Mafiosi, and demanded a tribute from each of them. They didn't like this, and so Luciano arranged to eliminate Maranzano. He cleverly didn't try to declare himself capo di tutti capi. Instead, by forming the Commission, he gave nine Dons an "equal" voice--but his voice was more equal than the others' because he headed the Commission.
The Commission never had a charter to run organized crime in America, to adjudicate murders, to approve men about to be "made," or most of the other policy-making roles or operational powers people would like to think that it had. The Commission never had, and still doesn't have, a "war chest" or a squad of hit men, to assassinate Mob turncoats or undercover cops like Joe Pistone. It was originally intended to provide a forum for Mob bosses to talk to each other before fighting, so that they might cooperate instead of shooting each other. For example, some people think that the famously aborted Apalachin, NY, meeting of 1957 was called to anoint Carlo Gambino as Albert Anastasia's successor. Nonsense! That was a fait accompli by that time. The meeting was called by Vito Genovese to set up an international cartel to oversee importation, distribution and sales of drugs. Thereafter, the Commission never met more frequently than once every 18 months.
Keep in mind, too, that Mafia families are inherently greedy, self-centered and individualistic, disinclined to do things that others want them to do. They cooperate only when there's a (very rare) consensus. When the Commission tried to replace Joe Bonanno as head of his family, he refused to cooperate, setting off the long, destructive, "Bananna Wars." Bonanno eventually retired, but the Commission was weakened by its failure and never recovered.
