Continuity of government
From dKosopedia
The concept of continuity of government refers to the laws and procedures which are in place to ensure the continuous, effective operation of the government even in the face of catastrophe, whether natural or man-made, such as terrorist attack or nuclear war.
In the U.S., the best-known measures to ensure continuity of government are those related to the order of Presidential succession, but during the Cold War similar processes were put in place for Congress, the judicial branch, and the various departments of the executive branch.
The subject again became a matter of great interest following the terrorist attacks of September 11, 2001. Along with Congressional hearings on the matter, a private commission called the Continuity of Government Commission, headed by Lloyd Cutler and Alan Simpson, is also investigating possible reforms in the area.