Wow. This is begging - begging! - for a big fat stack of social engineering. You can fake being an FBI man and get into the library records of anyone you want. They're under gag order and they know it, so they won't look into it at all. Just run a line on the librarian about the Patriot Act and federal felony charges if they do anything to breach the secrecy of the inquiry, including looking into it. Even casual checking might reveal to the librarian that they're getting conned, but they can't check, or if they do check they have to do all the checking themselves without telling anyone why! Throw in some bullshit about how open phone lines arn't regarded as secure, and you can convince them that they can't even call the FBI to check your id!

Christmas comes early this year for the black hats! How many other gag orders like this exist under the patriot act? How many people are hindered in finding out if inquiries are coming from a valid source? How many shady groups are already using this enviornment of secrecy to reach thier nefarious ends?