Every member of Congress--but particularly the chairs of the intelligence committees--needs to read today's explosive Wall Street Journal article before considering moving forward on any FISA legislation.

Five years ago, Congress killed an experimental Pentagon antiterrorism program meant to vacuum up electronic data about people in the U.S. to search for suspicious patterns. Opponents called it too broad an intrusion on Americans' privacy, even after the Sept. 11 terrorist attacks.

But the data-sifting effort didn't disappear. The National Security Agency, once confined to foreign surveillance, has been building essentially the same system.

The central role the NSA has come to occupy in domestic intelligence gathering has never been publicly disclosed. But an inquiry reveals that its efforts have evolved to reach more broadly into data about people's communications, travel and finances in the U.S. than the domestic surveillance programs brought to light since the 2001 terrorist attacks....

Two former officials familiar with the data-sifting efforts said they work by starting with some sort of lead, like a phone number or Internet address. In partnership with the FBI, the systems then can track all domestic and foreign transactions of people associated with that item -- and then the people who associated with them, and so on, casting a gradually wider net. An intelligence official described more of a rapid-response effect: If a person suspected of terrorist connections is believed to be in a U.S. city -- for instance, Detroit, a community with a high concentration of Muslim Americans -- the government's spy systems may be directed to collect and analyze all electronic communications into and out of the city.

The haul can include records of phone calls, email headers and destinations, data on financial transactions and records of Internet browsing. The system also would collect information about other people, including those in the U.S., who communicated with people in Detroit....

Two current officials also said the NSA's current combination of programs now largely mirrors the former TIA project. But the NSA offers less privacy protection. TIA developers researched ways to limit the use of the system for broad searches of individuals' data, such as requiring intelligence officers to get leads from other sources first. The NSA effort lacks those controls, as well as controls that it developed in the 1990s for an earlier data-sweeping attempt.

Sen. Ron Wyden, an Oregon Democrat and member of the Senate Intelligence Committee who led the charge to kill TIA, says "the administration is trying to bring as much of the philosophy of operation Total Information Awareness as it can into the programs they're using today." The issue has been overshadowed by the fight over telecoms' immunity, he said. "There's not been as much discussion in the Congress as there ought to be."