Rule XXI of the Standing Rules of the United States Senate, established by the Senate Committee on Rules and Administration, governs closed sessions of the Senate.
Contents
Motion to Close Doors
Paragraph 1 states that if a Senator determines that discussion of business requires secrecy, that a motion be made to close the doors and that it be seconded. The Presiding Officer of the United States Senate shall direct the galleries to be cleared; and during the discussion of such motion the doors shall remain closed.
Meeting Within Closed Doors
Paragraph 2 states that when the Senate meets in closed session, any applicable provisions of Rule XXIX and Rule XXXI, including the confidentiality of information shall apply to any information and to the conduct of any debate transacted.
References
Standing Rules of the United States Senate, Rule XXI Wikipedia(Text) CC BY-SA