That ensure "continuity of government".
This is otherwise known as "Octopus" or the "Shadow Government".
http://www.amazon.com/exec/obidos/tg/detail/-/092291589X/104-1707464-9506317?v=glanceFrom Publishers Weekly
What if, on September 11, 2001, United flight 93 had crashed into the Capitol, as some believe the terrorists had planned? Helms, an expert on clandestine and pirate radio, offers a nightmare scenario for what might have followed: the president could have declared a state of emergency and an unelected "shadow government," housed in hidden bunkers, would have gone into operation; civil liberties would have been suspended; civilian authorities in various cities would yield to military Special Forces. Is all this legal? Yes, according to Helms-a series of laws passed during WWII and after have concentrated much power in the president and created a Continuity of Government program in the event of a national emergency. Helms describes at length the past uses of executive orders to subvert civil liberties, such as FDR's order 9066, which led to the detention of Japanese-Americans, looks at the role of the Federal Emergency Management Agency ("the scariest agency in the entire government"), and sweeping security steps that have been contemplated in the wake of September 11. Readers concerned with the possible loss of civil liberties will find their worst fears confirmed here.
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