G.P.O. versus G.P-O: A chronicle of mail art on trial is a publication of Genesis P-Orridge’s collection of materials surrounding Great Britain’s General Post Office’s case against him for disseminating pornographic material through the mail in 1975. These postcards incorporated confrontational images with images of the Queen. When the Post Office made their case against P-Orridge, it became an opportunity to turn the case into another performance. G.P.O. versus G.P-O collects ephemera, legal documents, correspondence, and articles about the case and mail art. Genesis P-Orridge is an artist, musician and performer who founded the performance group, COUM Transmissions in 1969. They were active until 1976 when they mounted their controversial exhibition, Prostitution, at the Institute of Contemporary Art in London. G.P.O vs. G.P-O is a reprint of Ecart Publications’ 1976 edition.