The civil liberties advocacy group released a government-censored version of the lawsuit Thursday. The case originally was filed under seal August 9 in U.S. District Court in Bridgeport, Connecticut, because the law under which the FBI acted bars the organization or its attorneys from "disclosing to any person" that the FBI has demanded information.

ACLU Associate Legal Director Anne Beeson said the FBI and Justice Department had censored the document and allowed release of that version.

The ACLU said its client "possesses a wide array of sensitive information about library patrons, including information about the reading materials borrowed by library patrons and about Internet usage by library patrons."

The censored document makes clear the client is a member of the American Library Association.

The document strongly suggests the client is a library or library system and its manager. But because of provisions of the law used by the FBI and the fact that some businesses that supply libraries are members of the library association, it was at least possible the client is a business that provides Internet access to a library system. Beeson said the government would not allow her to clarify that.

U.S. District Judge Janet Hall has scheduled an August 31 hearing in Bridgeport on the group's request to lift the gag order so its client can participate in debate over the Patriot Act, which Congress is considering reauthorizing.

"Our client wants to tell the American public about the dangers of allowing the FBI to demand library records without court approval," Beeson said. "If our client could speak, he could explain why Congress should adopt additional safeguards that would limit Patriot Act powers."

Justice Department spokesman Charles Miller declined to comment on the ACLU lawsuit or on the number of such requests the government has made. The FBI also declined to comment.

With key information blacked out, the released document reveals very little of the underlying case.

On an undisclosed date, the FBI delivered what is known as a National Security Letter to the ACLU's client demanding "any and all subscriber information, billing information and access logs of any person or entity related to" something or someone which is blacked out. It said the information is relevant to an investigation of terrorism or spying.

Issued by the FBI without review by a judge, National Security Letters were authorized in 1986 by the Electronic Communications Privacy Act. The are used to obtain electronic records from "electronic communications service providers."

Such providers are not limited to Internet service companies but now also include universities, public interest organizations and almost all libraries, because most provide access to the Internet.

The original act allowed the FBI to get records of a person or group suspected of acting on behalf of a foreign power, or under 1993 amendments, the records of someone thought to be communicating with such a foreign agent about international terrorism.

The Patriot Act in 2001 removed the requirement that the records sought be those of someone under suspicion. Now an innocent person's records can be obtained if the FBI considers them relevant to a terrorism or spying investigation.

Last September in another ACLU lawsuit, a federal judge in New York struck down this provision of law as unconstitutional under the First and Fourth Amendments on grounds that it restrains free speech and bars or deters judicial challenges to government searches. That ruling is suspended pending an appeal to the 2nd U.S. Circuit Court of Appeals.

Because this Patriot Act provision was enacted permanently in 2001, it was not part of Congress' debate this summer over extension of some Patriot Act provisions. But Beeson said the House bill extending the Patriot Act would amend this provision "to explicitly make it a crime for our client in this case to talk -- even to contribute to the Patriot Act debate." The Senate bill does not contain that provision.

Neither the House nor Senate versions of the Patriot Act extension would forbid anything the FBI did in this case, Beeson said. Congress will resume debate on the Patriot Act extension this fall.