After Watergate, revelations about FBI excesses under J. Edgar Hoover and news the CIA had been spying domestically on antiwar protesters, distrust of the government was at an all-time high.
Two commissions to investigate the abuses resulted in the erection of an institutional wall that prevented FBI (search) agents conducting criminal investigations from seeking information from FBI or CIA (search) agents involved in intelligence gathering.
In the summer of 2001, hijackers Khalid Al-Mihdar and Nawaf Al-Hazmi were already in the United States. But the wall was so solidly in place that criminal investigators at the FBI field office in New York were actively blocked from obtaining intelligence information about the two men.
Just 13 days before the Sept. 11 attacks, a frustrated New York agent fired off an e-mail to FBI headquarters, stating, "Someday someone will die, and wall or not, the public will not understand why we were not more effective and throwing every resource we had at certain problems ... The biggest threat to us now, [Usama Bin Laden], is the getting the most 'protection.'"
This wall was torn down by the Patriot Act (search), and at Tuesday's hearings before the National Commission on Terror Attacks Upon the United States, wide-ranging support for making the provisions of the Patriot Act permanent was voiced.
Click here to watch a report by Fox News Channel's Brian Wilson.