The 199-page report, which found "serious misuse" of the surveillance power (PDF), says that FBI field agents unlawfully accessed telephone companies' internal databases showing calling records, and repeatedly sought and obtained information that federal law does not permit to be disclosed without a judge's approval.
Inspector General Glenn A. Fine oversaw the creation of the report, which reviewed the FBI's use of. The 2001 Patriot Act expanded the FBI's ability to use those letters--which do not require court approval--to obtain confidential information on Americans from banks, credit card companies, credit bureaus, telephone companies and Internet service providers.
Fine said, however, that there was no evidence that the FBI agents' unlawful activities "constituted criminal misconduct." Unlike conducting an unlawful wiretap, which is a federal felony, unlawful use of national security letters carries no criminal penalties.
Friday's disclosure of the FBI's slipshod use of the secret investigative technique (recipients are not permitted to disclose the letter's existence) reverberated quickly and loudly on Capitol Hill and inside the Bush administration.
FBI Director Robert Mueller called a news conference in Washington during which he took responsibility for the wrongdoing. Attorney General Alberto Gonzales sent a letter to Inspector General Fine saying that "the problems identified in your review are serious and must be addressed immediately." Neither disputed the report's conclusions.
Among members of Congress, both Republicans and Democrats said they would try to find out what led to widespread abuse of the national security letter process.
, a Wisconsin Democrat, said he would press for "quick Senate reforms" to stop abuses and said he expected the Judiciary and Intelligence committees would conduct full and prompt investigations.
Sen. Arlen Specter, a Pennsylvania Republican, said that the Judiciary Committee will have to "undertake comprehensive oversight on this important matter and perhaps act to limit the FBI's power by revising the Patriot Act."
Among the report's findings:
A review of a representative sample of 77 FBI investigative files showed that 17 of them--22 percent--contained "one or more possible violations relating to national security letters that were not identified by the FBI."
The FBI underreported its use of national security letters to Congress. A spot check of four FBI field offices showed that requests made by the secret letters were underreported by 22 percent.
The FBI's use of national security letters has "grown dramatically since the enactment of the Patriot Act." In 2000, the last full calendar year before the September 11 attacks, the FBI sent about 8,500 requests. During the following three-year period ending in 2005, the FBI sent a total of 143,074 requests.
An increasing number of U.S. citizens and residents have been targeted during that three-year period. About 39 percent of national security letters related to U.S. citizens and residents in 2003; two years later it had climbed to about 53 percent of requests.