In the United States government, executive privilege is the power claimed by the President of the United States and other members of the executive branch to resist certain subpoenas and other interventions by the legislative and judicial branches of government to access information and personnel relating to the executive branch. The concept of executive privilege is not mentioned explicitly in the United States Constitution, but the Supreme Court of the United States ruled it to be an element of the separation of powers doctrine and derived from the supremacy of executive branch in its own area of Constitutional activity.
The Supreme Court confirmed the legitimacy of this doctrine in United States v. Nixon, but only to the extent of confirming that there is a qualified privilege. Once invoked, a presumption of privilege is established, requiring the Prosecutor to make a "sufficient showing" that the "Presidential material" is "essential to the justice of the case" (418 U.S. at 713-14). Chief Justice Burger further stated that executive privilege would most effectively apply 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 the United States Congress and the courts over the issue by first asserting the privilege, then producing some of the documents requested on an assertedly voluntary basis.
Executive privilege is a specific instance of the more general common-law principle of deliberative process privilege and is believed to trace its roots to the English Crown Privilege.