There are three categories of presidential power:
Constitutional and delegated powers make up the expressed powers because these powers are clearly outlined in the Constitution. Presidents have interpreted inherent powers differently, sometimes in ways that grant the president great power.
The most common inherent powers are emergency powers, exercised only in times of great need. Some emergency powers are limited in scope. The president can declare a place devastated by a storm a federal disaster area, making it eligible for federal aid. Other emergency powers are much vaster in scope. During the Civil War, for example, President Abraham Lincoln spent money without congressional approval, and he also suspended a number of civil liberties, including the writ of habeas corpus.
Another type of inherent power is the executive order, which is a rule or regulation issued by the president that has the force of law. The president can issue executive orders for three reasons:
All executive orders must be published in the Federal Register, the daily publication of federal rules and regulations.
Executive privilege is the right of officials of the executive branch to refuse to disclose some information to other branches of government or to the public. It includes refusing to appear before congressional committees. Executive privilege is an inherent power that is not clearly defined, and the courts have had to set limitations on the use of the privilege. In 1974, for example, the Supreme Court ruled that executive privilege could not be invoked to prevent evidence from being used in criminal proceedings against the president.