All from Wiki....which is not alway true.
Executive Privilege is the power claimed by the President of the United States and other members of the executive branch to resist certain search warrants and other interventions by the legislative and judicial branches of government. The concept of executive privilege is not mentioned in the United States Constitution, but some consider it to be an element of the separation of powers doctrine, and/or derived from the supremacy of executive branch in its own area of Constitutional activity.[1]
Presidents since George Washington and Thomas Jefferson have argued that each branch of government may operate with some degree of freedom from the control or supervision of the others.[citation needed] The Supreme Court confirmed the legitimacy of this doctrine in United States v. Nixon, but only to the extent of confirming that it can be invoked when the oversight of the executive would impair that branch's national security concerns.
Historically, the uses of executive privilege underscore the untested nature of the doctrine, since Presidents have generally sidestepped open confrontations with Congress and the courts over the issue by first asserting the privilege, then producing some of the documents requested on an assertedly voluntary basis.
See bold highlighted area......
Nuff said....bush is a crimial.....what is he trying to hide?