"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 vice presidency performs functions in both the legislative branch . . . and in the executive branch." -- the "Plum Book", a government directory.
It's interesting how the different news agencies have been spinning the story about Cheney refusing to comply with an executive order related to reporting how classified documents are handled. The Star Trib played the "Cheney says he's in the legislative branch, how wacky" angle quite strongly.
Time magazine: The Cheney Branch of Government.
The Guardian article (White House Defends Cheney Over Secrets) choice of Steven Aftergood to provide the legal interpretation is a bit odd, but on point:
Steve Aftergood, director of the Federation of American Scientists' government secrecy project, said the executive order defines ``agency'' as any executive agency, military department and ``any other entity within the executive branch that comes into the possession of classified information.''
If Cheney's office is not part of the executive branch, ``they're going to have to rewrite the textbooks,'' Aftergood said.
Dan Froomkin goes on for quite some length: Cheney: Neither Here Nor There? The Method to Cheney's Madness.
Hmm... under Cheney's theory, then, the Chief Justice should be part of the legislature as well, since he presides over impeachments of the President...