We told the FBI that it would have to follow legal channels before our board of trustees would address releasing the names of the borrowers. We also informed the FBI that, through a Google search, our attorney had discovered that the words in the margin were almost identical to a statement by bin Laden in a 1998 interview.

Undeterred, the FBI served a subpoena on the library a week later demanding a list of everyone who had borrowed the book since November 2001.

Our trustees faced a difficult decision. It is our job to protect the right of people to obtain the books and other materials they need to form and express ideas. If the government can easily obtain records of the books that our patrons are borrowing, they will not feel free to request the books they want. Who would check out a biography of bin Laden knowing that this might attract the attention of the FBI?

It is for this reason that libraries across the country have taken a strong stand against government intrusion. In the 1980s, it was revealed that the FBI had engaged in a secret "library awareness" program to track the books borrowed by patrons who had emigrated from communist countries. Determined to prevent such activities in the future, librarians helped pass laws in 48 states that bar the surrender of customer information except in compliance with a subpoena.

For our trustees, this sense of responsibility to protect libraries as institutions where people are free to explore any idea ran up against their desire to help their government fight terrorism. But they were resolute and voted unanimously to go to court to quash the FBI subpoena. Fifteen days later, the FBI withdrew its request.

But there is a shadow over our happy ending. Our experience taught us how easily the FBI could have discovered the names of the borrowers, how readily this could happen in any library in the USA. It also drove home for us the dangers that the USA Patriot Act poses to reader privacy.

Since the passage of the Patriot Act in October 2001, the FBI has the power to go to a secret court to request library and bookstore records considered relevant to a national security investigation. It does not have to show that the people whose records are sought are suspected of any crime or explain why they are being investigated. In addition, librarians and booksellers are forbidden to reveal that they have received an order to surrender customer data.

Our government has always possessed the power to obtain library records, but that power has been subject to safeguards. The Patriot Act eliminated those safeguards and made it impossible for people to ask a judge to rule whether the government needs the information it is after. In the current debate over extending or amending the Patriot Act, one of the key questions is whether a library or any other institution can seek an independent review of an order. Even the attorney general conceded in a recent oversight hearing that this is a problem with the law as written.

Fortunately for our patrons, we were able to mount a successful challenge to what seems to have been a fishing expedition. If it had returned with an order from a secret court under the Patriot Act, the FBI might now know which residents in our part of Washington State had simply tried to learn more about bin Laden.

With a Patriot Act order in hand, I would have been forbidden to disclose even the fact that I had received it and would not have been able to tell this story.

Joan Airoldi, a librarian, is director of the library district in Whatcom County, Wash.