In the George W. Bush Administration, Vice President Dick Cheney advanced the idea that the Office of the Vice President is not part of the executive branch, and that it was therefore exempt from the sort of oversight mechanisms — including classification oversight — which it might otherwise be (and previously was in fact) subject to.
Somewhat unexpectedly, this conception of a Vice Presidency that transcends the three branches of government reappears in the 2012 edition of the Plum Book, an official publication which lists thousands of employment positions for appointees within the federal government and which is published every four years.
“The Vice Presidency is a unique office that is neither a part of the executive branch nor a part of the legislative branch, but is attached by the Constitution to the latter,” the new 2012 Plum Book states in Appendix No. 5, reproducing identical language from the 2008 Plum Book.
This language was first introduced in 2004, when that year’s Plum Book also stopped listing most of the previously identified staff positions in the Office of Vice President, with the exception of the Chief of Staff (I. Lewis Libby) and one other assistant.
By 2008, even those two staff listings had been deleted from the Plum Book as the Office of the Vice President retreated into further concealment.
Thirteen current OVP positions are now listed. And the Office of the Vice President appears — as it did prior to the Bush Administration — under the heading of the Executive Branch.
Update: The statement that the Vice Presidency “belongs neither to the Executive nor to the Legislative Branch but is attached by the Constitution to the latter” is derived from a 1961 Office of Legal Counsel opinion (at p. 11), which termed the question a “semantic problem.” Under the George W. Bush Administration, however, this semantic problem was invoked to alter established oversight practices in the direction of greater secrecy.