From the paper:
“The actual phrase, ?Executive Privilege,? was not a part of the common language until the Eisenhower administration. The first time the term was used occurred in 1954 when Senator Joseph McCarthy was investigating the Eisenhower administration. McCarthy had planned to subpoena Eisenhower’s chief of staff, but Eisenhower told his advisers that Congress had no right to ask White House personnel to testify in any manner concerning conversations with the President at any time on any subject.