1. Does Vice-President Cheney have the legal authority to declassify material single-handedly?
2. And even if he does, if Cheney proved also to be the source of an instruction to leak information about Valerie Plame, does his legal authority extend to the exposing the identity of a covert CIA agent?
3. And if the answer to either question above is "no" does that amount to an impeachable offense?
But the Plame leak is a much trickier issue. If it proved to be the case that Cheney ordered the outing of Plame without authority and with the knowledge that she was a covert operative then I think given that Congress has made clear by statute that this is a special circumstance, this leak does rise to the sort of 'high crime' that is an impeachable offense. It was something that directly weakened the US by exposing an agent, ruining her value to the CIA and also her career, and it was done for vile, partisan purposes, perhaps even in part as personal payback.
http://www.discourse.net/archives/2006/02/decreasingly_hypothetical_questions.htmlhttp://www.thewashingtonnote.com/archives/001253.phphttp://www.liberaloasis.com/archives/021206.htm#021606Since everyone in the executive branch is subordinate to the President, the President can declassify at will (except for specific items that are outlawed by Congress, say for example, the identities of covert agents).
There are several specific categories of classified information that are protected by statute -- communications intelligence, identities of covert agents, nuclear weapons design information, and some others. Those statutes are binding on the executive branch as well as on everyone else.
Is leaking the identity of a CIA operative illegal? Yes, under the terms of the Intelligence Identities Protection Act.