Giuliani was a Mafia buff. Giuliani's brilliant insight as US Attorney for the Southern District of NY came when he read Joseph Bonanno's autobiography, "A Man of Honor." He recognized in Bonanno's detailed account of the workings of the Commission that it was a "Racketeer Influenced and Corrupt organization" as described in the RICO Act.

RICO had been passed by Congress years earlier, but Federal prosecutors were reluctant to use it because they really didn't understand how to bring cases under RICO that would win. Giuliani invited G. Robert Blakey, the author of the RICO Act, to brief him and his team on how to apply RICO to the NY Five Families Dons. He brought convictions in the "Commission Case," and sent away three Dons for 100-year sentences.