"The Carnivore system was a Microsoft Windows-based workstation with packet-sniffing software and a removable disk drive. This computer must be physically installed at an Internet service provider (ISP) or other location where it can "sniff" traffic on a LAN segment to look for email messages in transit. The technology itself was not highly advanced — it used a standard packet sniffer and straightforward filtering. The critical components of the operation were the filtering criteria. To accurately match the appropriate subject, an elaborate content model was developed" (Wikipedia article on Carnivore, accessed 01-14-2012).
"On July 11, 2000, the existence of an FBI Internet monitoring system called "Carnivore" was widely reported. Although the public details were sketchy, reports indicated that the Carnivore system is installed at the facilities of an Internet Service Provider (ISP) and can monitor all traffic moving through that ISP. The FBI claims that Carnivore "filters" data traffic and delivers to investigators only those "packets" that they are lawfully authorized to obtain. Because the details remain secret, the public is left to trust the FBI's characterization of the system and -- more significantly -- the FBI's compliance with legal requirements.
"One day after the initial disclosures, EPIC filed a Freedom of Information Act (FOIA) request seeking the public release of all FBI records concerning Carnivore, including the source code, other technical details, and legal analyses addressing the potential privacy implications of the technology. On July 18, 2000, after Carnivore had become a major issue of public concern, EPIC asked the Justice Department to expedite the processing of its request. When DOJ failed to respond within the statutory deadline, EPIC filed suit in U.S. District Court seeking the immediate release of all information concerning Carnivore.
"At an emergency hearing held on August 2, 2000, U.S. District Judge James Robertson ordered the FBI to report back to the court by August 16 and to identify the amount of material at issue and the Bureau's schedule for releasing it. The FBI subsequently reported that 3000 pages of responsive material were located, but it refused to commit to a date for the completion of processing.
"In late January 2001, the FBI completed its processing of EPIC's FOIA request. The Bureau revised its earlier estimate and reported that there were 1756 pages of responsive material; 1502 were released in part and 254 were withheld in their entirety (see link below for sample scanned documents).
"On August 1, 2001, the FBI moved for summary judgment, asserting that it fully met its obligations under FOIA. On August 9, 2001, EPIC filed a motion to stay further proceedings pending discovery, on the grounds that the FBI has failed to conduct an adequate search for responsive documents.
"On March 25, 2002, the court issued an order directing the FBI to initiate a new search for responsive documents. The new search was to be conducted in the offices of General Counsel and Congressional & Public Affairs, and be completed no later than May 24, 2002. The documents listed above were located and released as a result of that court-ordered search" (http://epic.org/privacy/carnivore/, accessed 01-14-2012).