called Hoover to find out who might have leaked this information to the press. Hoover suggested Halperin, and Kissinger agreed that was likely. That day, the FBI began tapping Halperin's phones at Kissinger's direction. The Nixon administration bugged Halperin's home phone, without a warrant, for 21 months starting in 1969. Halperin also ended up on Nixon's Enemies List of 20 people with whom the White House was unhappy with because they disagreed in some way with the administration. Halperin was number 8 on the list. Nixon aide Charles Colson, who compiled the list, wrote next to Halperin's name, "a scandal would be helpful here." Defense Secretary Robert MacNamara asked Halperin to oversee the production of the Pentagon Papers. Les Gelb, a member of Halperin's staff, oversaw the staff that actually wrote the study. Halperin was a friend of Daniel Ellsberg. When Ellsberg was investigated in connection with the Pentagon Papers, suspicion fell on Halperin, who some Nixon aides believed had kept classified documents when he left government service. The tapping of Halperin's phone without a warrant was discovered when it came out in Ellsberg's trial. Despite the continued use of the wiretap well after Halperin left government, Kissinger told reporters on May 13, 1973, that, "I never received any information that cast any doubt on [Halperin's] loyalty and discretion." Halperin sued in federal court. Halperin won a symbolic $1 judgment in 1977 for the offense, but the judgment was overturned by an appeals court. In 1991, Kissinger apologized to Halperin in a letter and the suit was dropped at Halperin's request in 1992. Positions between government service After leaving the Nixon administration, Halperin joined the Brookings Institution as a senior fellow from 1969 to 1973 and then became the research director for the Project on Information, National Security and Constitutional Procedures at the Twentieth Century Fund from 1974 to 1975. He was the director for the Project on National Security and Civil Liberties from 1975 to 1977. From 1977 to 1992, he served as the director of the Center for National Security Studies (jointly sponsored by the Fund for Peace and the American Civil Liberties Union Foundation. And from 1992 to 1994, he was a senior associate at the Carnegie Endowment for International Peace. American Civil Liberties Union (ACLU) From 1984 to 1992, Halperin served as director of the American Civil Liberties Union (ACLU) office in Washington. While at the