The LA Times gives the background on Cheney's claim to be a fourth branch of government:

One Cheney staffer familiar with the matter said Thursday that the vice president has not complied with the order because his office has dual functions: It is part of the executive branch — the Bush administration — but also part of the legislative branch, given Cheney's position as president of the Senate.

As such, the vice president's office has no legal obligation to abide by the order because it only applies to the executive branch, said the Cheney staffer, who was not authorized to publicly discuss the inner workings of the office and requested anonymity.

Cheney's position is articulated in the 2004 edition of an annual government directory of senior officials known as the Plum Book:

"The vice presidency is a unique orifice 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."

Oops! "Office!" Office, not orifice! I misspoke.

Sorry. Sorry, FCC.

NOTE I believe it was TPM that first brought this swelling sack of pus in the Office of the Vice President to our attention. As a legal scholar not chained up in the dank basement of Cheney's bunker comments:

Gordon Silverstein, a constitutional scholar at UC Berkeley, said Cheney's claims were all the more noteworthy given his repeated assertions of executive privilege, based on his senior position within the Bush administration, as a reason why he has not had to testify before Congress or provide lawmakers with information on such national security issues as torture, interrogation and CIA renditions of terrorists.

"Here's a guy who raises 'executive privilege' to historic levels to exempt himself from all rules and oversight, and now he says he's not part of the executive branch?" said Silverstein. "Here we have a subordinate part of the executive branch asserting independent constitutional authority even against its own superior. It is flabbergasting."

Well, the depredations of the Bush adminsitration have been "flabbergasting" since, oh, election 2000. And the depredations of the conservative movement, the fragrant dungheap in which Cheney's flower of Constitutional doctrine took root have been "flabbergasting" since the slow-moving, media-fuelled, conservative coup that began with the Whitewater and culminated with their seizure of power in Bush v. Gore.

Still, it's good to see somebody other than us DFH types taking notice. At long last.