Executive privilege is the right of the president of the United States and other members of the executive branch to maintain confidential communications under certain circumstances within the executive branch and to resist some subpoenas and other oversight by the legislative and judicial branches of government in pursuit of particular information or personnel relating to those confidential communications. The right comes into effect when revealing information would impair governmental functions. Neither executive privilege nor the oversight power of Congress is explicitly mentioned in the United States Constitution. However, the Supreme Court of the United States has ruled that executive privilege and congressional oversight each are a consequence of the doctrine of the separation of powers, derived from the supremacy of each branch in its own area of Constitutional activity.