Gerard C. Smith, 80, key nuclear disarmament negotiator who advised four U.S. Presidents. He received the Medal of Freedom, the nation's highest civilian award, from President Jimmy Carter for his decades of work. Smith served in the Eisenhower and Kennedy Administrations and was director of the Arms Control and Disarmament Agency during the Nixon Administration. Under Carter, he held the title ambassador-at-large for nuclear non-proliferation. Smith was chief negotiator for the Strategic Arms Limitation Talks from 1969 to 1973, and was also credited with establishment of a hot line between Washington and Moscow to reduce the possibility of accidental nuclear confrontation. He also won recognition for writing (with McGeorge Bundy and Robert S. McNamara) a 1982 article urging the United States to pledge that it would not initiate a nuclear confrontation. On July 4 in Easton, Md., of cancer.