In the 1980s Richard Cheney and Donald Rumsfeld discussed just such emergency surveillance and detention powers in a super-secret program that planned for what was euphemistically called "Continuity of Government" (COG) in the event of a nuclear disaster.
and that
These men planned for suspension of the Constitution, not just after nuclear attack, but for any "national security emergency," which they defined in Executive Order 12656 of 1988 as: "Any occurrence, including natural disaster, military attack, technological or other emergency, that seriously degrades or seriously threatens the national security of the United States." Clearly 9/11 would meet this definition..
via gabriella@dkos