Rudolph William Louis "Rudy" Giuliani (; born May 28, 1944) is an American lawyer, businessman, former politician, and public speaker from New York. Politically a Democrat and then an Independent in the 1970s, but a Republican since the 1980s, Giuliani was the United States Attorney for the Southern District of New York during the 1980s and prosecuted pivotal cases against the American Mafia and against corrupt corporate financiers. Giuliani tamed organized crime—most famously leading the case that sent boss John Gotti, the "Teflon Don," to prison for life based on testimony brokered in a deal with Sammy "The Bull" Gravano. That accomplishment, which won Giuliani a reputation for being tough on crime, helped to launch his political career.