by Stuart Taylor Jr.

About the author: Stuart Taylor Jr. is a senior writer and columnist on legal affairs for the National Journal,a weekly magazine covering politics and government, and a contributing editor at Newsweek.

One [FBI] agent, frustrated at encountering the “wall” [separating intelligence officials from criminal investigators], wrote to headquarters [on Aug. 29, 2001]: “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, [terrorist] UBL [Osama bin Laden], is getting the most ‘protection.’”

—Opinion of Foreign Intelligence Surveillance Court of Review, November 18, 2002

Complexity can confound clear thinking and facilitate false alarms. Such has been...