'Have you ever filed a Freedom of Information Act (FOIA) request with the FBI and received a written response from the agency stating that it could not locate records responsive to your request?

If so, there's a chance the FBI may have found some documents, but for unknown reasons, the agency's FOIA analysts determined it was not responsive and "blackballed" the file, crucial information the FBI withholds from a requester when it issues a "no records" response.

The FBI's practice of "blackballing" files has never been publicly disclosed before. With the exception of one open government expert, a half-dozen others contacted by Truthout said they were unfamiliar with the process of "blackballing" and had never heard of the term.'

Read more: Revealed: The FBI's Secretive Practice of 'Blackballing' Files