The five rolls of 35 mm film known as the "pumpkin papers" had been characterized as highly classified and too sensitive to reveal and were thought until late 1974 to be locked in HUAC files. In 1975, independent researcher Stephen W. Salant, an economist at the University of Michigan, sued the U.S. Justice Department when it denied his request for access to them under the Freedom of Information Act. On July 31, 1975, as a result of this lawsuit and follow-on suits filed by Peter Irons and by Alger Hiss and William A. Reuben, the Justice Department released copies of the "pumpkin papers" that had been used to implicate Hiss. One roll of film turned out to be totally blank due to overexposure,