Beginning with a reported precursor in January 1940, the U.S. Army arranged for RCA employee Earle F. Cook to photograph international commercial cablegrams. During World War II, cables were turned over to the government for inspection, and the arrangement continued after the war as Project SHAMROCK. The Armed Forces Security Agency and later the NSA received daily microfilm copies of incoming, outgoing, and transiting telegrams from Western Union and associates RCA and ITT. No court authorized the operation and no warrants were obtained.
Intercepted material was distributed to the FBI, CIA, Secret Service, Bureau of Narcotics and Dangerous Drugs, and the Department of Defense. At its height, NSA personnel processed approximately 150,000 messages per month; a 1950s expansion also tapped communications links of 60–70 foreign embassies. Congressional investigations beginning in May 1975 exposed the program, prompting NSA Director Lew Allen to terminate it. Senate Intelligence Committee Chairman Frank Church called SHAMROCK “probably the largest government interception program affecting Americans ever undertaken.” A 1977 Justice Department review concluded that wiretap laws had been violated, and the scandal contributed to Congress’s creation of the Foreign Intelligence Surveillance Act in 1978, establishing warrant and judicial-review requirements.
