This law (FISA) has been on the books since 1978..Jimmy Carter issued an executive order allowing the AG to OK such wire taps without warrants.....I would guess he had a reason besides filling up a piece of paper for issuing the order....
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Judgments on who to monitor are made at the NSA, approved by an NSA shift supervisor and carefully recorded, Hayden said. "The reason I emphasize that this is done at the operational level is to remove any question in your mind that this is in any way politically influenced," he said.
_On the importance of the intelligence, Hayden said, "There are probably no communications more important to what it is we're trying to do to defend the nation ... than those communications that involve al-Qaida and one end of which is inside the homeland."
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http://news.yahoo.com/s/ap/20051219/ap_on_go_ca_st_pe/domestic_spying_box_2