After law school Giuliani clerked for Judge Lloyd MacMahon, United States District Judge for the Southern District of New York. In 1970, he joined the office of the U.S. Attorney. At age 29, he was named Chief of the Narcotics Unit and rose to serve as executive U.S. Attorney. In 1975, Giuliani was recruited by the [[Gerald R. Ford]] administration and became Associate Deputy Attorney General and chief of staff to the Deputy Attorney General. From 1977 to 1981 he practiced law at Patterson, Belknap, Webb and Tyler in New York City.<ref>"A Biography Of Mayor Rudolph W. Giuliani" The City of New York Office of the Mayor [http://www.nyc.gov/html/records/rwg/html/bio.html]</ref>
The Reagan Administration brought Giuliani to Washington in 1981 as Associate Attorney General, the third highest position in the [[U.S. Department of Justice]]. He supervised all of the US Attorney Offices' Federal law enforcement agencies, the Bureau of Corrections, the Drug Enforcement Agency, and the US Marshals. In 1983, Reagan appointed Giuliani to be US Attorney for the Southern District of New York. He gained national prominence over successfully prosecuting high -profile cases.
He frequently used the Racketeer Influenced and Corrupt Organizations Act (RICO) to bring down organized criminals. From 1985-1986 Giuliani indicted eleven organized crime figures under the RICO act that also included charges of extortion, labor racketeering, and murder for hire. Time Magazine called this "Case of Cases" possibly "the most significant assault on the infrastructure of organized crime since the high command of the [[Chicago]] Mafia was swept away in 1943." <ref>http://www.quickoverview.com/election2008/rudy-giuliani-overview.html</ref>