The FBI illegally collected more than 2,000 U.S. telephone call records between 2002 and 2006 by invoking terrorism emergencies that did not exist or simply persuading phone companies to provide records, according to internal bureau memos and interviews. FBI officials issued approvals after the fact to justify their actions.

E-mails obtained by The Washington Post detail how counterterrorism officials inside FBI headquarters did not follow their own procedures that were put in place to protect civil liberties. The stream of urgent requests for phone records also overwhelmed the FBI communications analysis unit with work that ultimately was not connected to imminent threats.

A Justice Department inspector general's report due out this month is expected to conclude that the FBI frequently violated the law with its emergency requests, bureau officials confirmed.

The records seen by The Post do not reveal the identities of the people whose phone call records were gathered, but FBI officials said they thought that nearly all of the requests involved terrorism investigations.

FBI general counsel Valerie Caproni said in an interview Monday that the FBI technically violated the Electronic Communications Privacy Act when agents invoked nonexistent emergencies to collect records.

"We should have stopped those requests from being made that way," she said. The after-the-fact approvals were a "good-hearted but not well-thought-out" solution to put phone carriers at ease, she said. In true emergencies, Caproni said, agents always had the legal right to get phone records, and lawyers have now concluded there was no need for the after-the-fact approval process. "What this turned out to be was a self-inflicted wound," she said.

Caproni said FBI Director Robert S. Mueller III did not know about the problems until late 2006 or early 2007, after the inspector general's probe began.

Documents show that senior FBI managers up to the assistant director level approved the procedures for emergency requests of phone records and that headquarters officials often made the requests, which persisted for two years after bureau lawyers raised concerns and an FBI official began pressing for changes.

"We have to make sure we are not taking advantage of this system, and that we are following the letter of the law without jeopardizing national security," FBI lawyer Patrice Kopistansky wrote in one of a series of early 2005 e-mails asking superiors to address the problem.

The FBI acknowledged in 2007 that one unit in the agency had improperly gathered some phone records, and a Justice Department audit at the time cited 22 inappropriate requests to phone companies for searches and hundreds of questionable requests. But the latest revelations show that the improper requests were much more numerous under the procedures approved by the top level of the FBI.

FBI officials told The Post that their own review has found that about half of the 4,400 toll records collected in emergency situations or with after-the-fact approvals were done in technical violation of the law. The searches involved only records of calls and not the content of the calls. In some cases, agents broadened their searches to gather numbers two and three degrees of separation from the original request, documents show.

Bureau officials said agents were working quickly under the stress of trying to thwart the next terrorist attack and were not violating the law deliberately.

FBI officials said they are confident that the safeguards enacted in 2007 have ended the problems. Caproni said the bureau will use the inspector general's findings to determine whether discipline is warranted.

The internal memos were obtained from a government employee outside the FBI, who gained access to them during the investigations of the searches. The employee spoke on the condition of anonymity because the release was unauthorized.

After the Sept. 11, 2001, attacks, the need to get information quickly and connect the dots was considered paramount throughout the federal government. The failure to obtain timely and actionable information has been a recurrent theme in the U.S. counterterrorism effort, up to and including the recent shootings at Fort Hood, Tex.

Before 9/11, FBI agents ordinarily gathered records of phone calls through the use of grand jury subpoenas or through an instrument know as a national security letter, issued for terrorism and espionage cases. Such letters, signed by senior headquarters officials, carry the weight of subpoenas with the firms that receive them.

The USA Patriot Act expanded the use of national security letters by letting lower-level officials outside Washington approve them and allowing them in wider circumstances. But the letters still required the FBI to link a request to an open terrorism case before records could be sought.

Shortly after the Patriot Act was passed in October 2001, FBI senior managers devised their own system for gathering records in terrorism emergencies.

A new device called an "exigent circumstances letter" was authorized. It allowed a supervisor to declare an emergency and get the records, then issue a national security letter after the fact.

The procedure was based on a system used in the FBI's New York office in the days immediately after the Sept. 11 suicide hijackings, officials said.

On Jan. 6, 2003, then-FBI Assistant Director for Counterterrorism Larry Mefford issued a bureau-wide communique authorizing the new tactic, saying the bureau's telephone analysis unit was permitted in "exigent circumstances . . . to obtain specialized toll records information for international and domestic numbers which are linked to subjects of pending terrorism investigations."

The e-mail called this new method of gathering phone records "imperative to the continuing efforts by the FBI to protect our nation against future attacks," even as it acknowledged the phone records of many people not connected to a terrorism investigation were likely to be scooped up.

The 2003 memo stated that the new method "has the potential of generating an enormous amount of data in short order, much of which may not actually be related to the terrorism activity under investigation."

Within a few years, hundreds of emergency requests were completed and a few thousand phone records gathered. But many lacked the follow-up: the required national security letters.

Two individuals began raising concerns.

Special Agent Bassem Youssef, the new supervisor of the communications analysis unit that gathered the records, began to receive complaints from phone companies that they had not received documentation to show the searches were legal.

Youssef, a longtime counterterrorism investigator, had earlier fallen out of favor with FBI management as he pursued a whistleblower claim that he had been wrongly retaliated against and denied promotion because of his ethnicity.

He raised questions in spring 2005 with his superiors and the FBI general counsel's office about the failure to get national security letters. E-mails show he pressed FBI managers, trying to "force their hand" to implement a solution.

Youssef's attorney, Stephen Kohn, said Monday that he could not discuss the specifics of the investigation except to confirm that his client cooperated with the inspector general. FBI officials said they could not discuss the conduct of individual employees.

Separately, Kopistansky in the FBI general counsel's office learned in mid-December 2004 that toll records were being requested without national security letters. She handled a request that originated from then-Executive Assistant Director Gary Bald, who had "passed information regarding numbers related to a terrorist organization with ties to the US" and obtained toll records, the memos show.

The communications analysis unit asked Kopistansky to "draw up an NSL" to cover the search, but she was unable to get superiors to tell her which open terrorism case it involved. The request "has to specify why the numbers are relevant to an authorized investigation," she said.

An employee in the communications analysis unit wrote back that most of the emergency requests he received "come from upper mgmt. I don't always receive documentation or know all the facts related to the number, which is a problem for me when I try to get the NSL."

Kopistansky persisted, demanding an open terrorism case file for the legal rationale. "I am sure you know it is true and Gary Bald knows it's true, but it needs to be reflected on a piece of paper," she wrote.

Two months later, Kopistansky was still unable to issue a national security letter to comply with the FBI rules.

She took note of the overall problem. The issuance of a national security letter after exigent searches "rarely happens," Kopistansky warned in a March 11, 2005, e-mail seeking the help of the FBI's top national security lawyer and the deputy counsel.

By March 2005, Kopistansky and Youssef were discussing a worsening "backlog" of other cases where no national security letters had been issued and growing concerned that exigent letters were being abused, e-mails show.

"I also understand that some of these are being done as emergencies when they aren't necessarily emergencies," Kopistansky wrote in an April 26, 2005, e-mail to Youssef.

Kopistansky and the other FBI lawyers discussed a strategy to handle the past emergency searches and to allow the practice to continue.

The e-mails show that they conceived the idea to open half a dozen "generic" or "broad" preliminary investigative (PI) case files to which all unauthorized emergency requests could be charged so a national security letter could be issued after the fact.

The generic files were to cover such broad topics as "threats against transportation facilities," "threats against individuals" and "threats against special events," the e-mails show.

Eventually, FBI officials shifted to a second strategy of crafting a "blanket" national security letter to authorize all past searches that had not been covered by open cases.

A November 2006 e-mail chain indicates that then-FBI Assistant Director for Counterterrorism Joseph Billy signed the blanket national security letter. But when FBI lawyers raised concerns about it, he wrote back that he did not remember signing.

"I have no recollection of signing anything blanket. NSLs are individual as far as I always knew," Billy wrote Caproni on Nov. 7, 2006.

Billy did not immediately respond to a message left at his office on Monday. Kopistansky and Bald, reached by phone Friday, said they could not comment without FBI approval. Mefford did not return calls.

In all, FBI managers signed 11 "blanket" national security letters addressing past searches, officials told The Post.

Although concerns about their legality first arose in December 2004, exigent searches continued for two more years. Youssef's unit began limiting the number of exigent letters it signed between summer 2005 and spring 2006, seeking more assurances the requests could be covered by a national security letter, the memos show.

Phone record searches covered by exigent letters ended in November 2006 as the Justice Department inspector general began investigating.

Among those whose phone records were searched improperly were journalists for The Washington Post and the New York Times, according to interviews with government officials.

The searches became public when Mueller, the FBI director, contacted top editors at the two newspapers in August 2008 and apologized for the breach of reporters' phone records. The reporters were Ellen Nakashima of The Post, who had been based in Jakarta, Indonesia, and Raymond Bonner and Jane Perlez of the Times, who had also been working in Jakarta.

Solomon, a former Post reporter and Washington Times editor, is a freelance journalist. Johnson is a Post staff writer.