If Iraq had succeeded in spray-drying anthrax spores to extend their life and lethality, that would have been among the most important secrets of its wide-ranging weapons program.

A national security letter cannot be used to authorize eavesdropping or to read the contents of e-mail. But it does permit investigators to trace revealing paths through the private affairs of a modern digital citizen.

In late 2003, the Bush administration reversed a long-standing policy requiring agents to destroy their files on innocent American citizens, companies and residents when investigations closed.

Barton Gellman Quotes