A very good topic would be the impact of the Racketeer Influenced Corrupt Organization (RICO) Act of 1970, which had a huge impact on the decline of the Mafia. For an excellent start, buy or borrow Selwyn Raab's superb "The Five Families," the best Mob book ever, which has an outstanding account of how RICO came into being, how it works, and how it was used. Following that, you'll have no difficulty finding RICO-related reading on the web and elsewhere.