Vice-President Cheney’s office is asserting that the Vice-President is not part of the Executive Branch:

For four years, Vice President Dick Cheney has resisted routine oversight of his officeâ€™s handling of classified information, and when the National Archives unit that monitors classification in the executive branch objected, the vice presidentâ€™s office suggested abolishing the oversight unit, according to documents released yesterday by a Democratic congressman.

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[O]fficials familiar with Mr. Cheneyâ€™s view said that he and his legal adviser, David S. Addington, did not believe that the executive order applied to the vice presidentâ€™s office because it had a legislative as well as an executive status in the Constitution. Other White House offices, including the National Security Council, routinely comply with the oversight requirements, according to Mr. Waxmanâ€™s office and outside experts.

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Mr. Addington stated in conversations that the vice presidentâ€™s office was not an â€œentity within the executive branchâ€ because, under the Constitution, the vice president also plays a role in the legislative branch, as president of the Senate, able to cast a vote in the event of a tie.