Security files were moved to the White House and Administration officials were banned from testifying before Congress on security related matters. Investigation of the State Department and other cases was stymied, and the matter was left unresolved. During the Army–McCarthy hearings in 1954, Eisenhower used the claim of executive privilege to forbid the "provision of any data about internal conversations, meetings, or written communication among staffers, with no exception to topics or people." Department of Defense employees were also instructed not to testify on such conversations or produce any such documents or reproductions. This was done to refuse the McCarthy Committee subpoenas of transcripts of monitored telephone calls from Army officials, as well as information on meetings between Eisenhower officials relating to the hearings. This was done in the form of a letter from Eisenhower to the Department of Defense and an accompanying memo from Eisenhower Justice. The reasoning behind the order was that there was a need for "candid" exchanges among executive employees in giving "advice" to one another. In the end, Eisenhower invoked the claim 44 times between 1955 and 1960. United States v. Nixon The Supreme Court addressed executive privilege in United States v. Nixon, the 1974 case involving the demand by Watergate special prosecutor Archibald Cox that President Richard Nixon produce the audiotapes of conversations he and his colleagues had in the Oval Office of the White House in connection with criminal charges being brought against members of the Nixon Administration for breaking into the Watergate complex. President Nixon invoked the privilege and refused to produce any records. The Supreme Court did not reject the claim of privilege out of hand; it noted, in fact, "the valid need for protection of communications between high Government officials and those who advise and assist them in the performance of their manifold duties" and that "[h]uman experience teaches that those who expect public dissemination of their remarks may well temper candor with a concern for appearances and for their own interests to the detriment of the decisionmaking process." The Supreme Court stated: "To read the Article II powers of the president as providing an absolute privilege as against a subpoena essential to enforcement of criminal statutes on no more than a generalized claim of the public interest in confidentiality of nonmilitary and nondiplomatic discussions would upset the constitutional balance of 'a workable government' and gravely impair the role of