Politicians’ papers are not only historical documents. They are also repositories of legal and evidential facts, as became clear in 1974 when Richard Nixon brokered an agreement that allowed him to retain control of thousands of hours of tape recordings. Congress was not happy. Later that year they passed the Presidential Recordings and Materials Preservation Act to regain control of the tapes. Nixon challenged the legislation in the courts, arguing that technology of this kind was not part of the national record but private property. In 1977 his appeal was rejected by the Supreme Court, and the National Archives began processing the tapes.