In a submission in the Jammie Thomas case, the MPAA has suggested to the judge that they don't really need to prove anything:
"It is often very difficult, and in some cases, impossible, to provide such direct proof when confronting modern forms of copyright infringement, whether over P2P networks or otherwise; understandably, copyright infringers typically do not keep records of infringement," van Uitert wrote on behalf of the movie studios, a position shared with the Recording Industry Association of America, which sued Thomas, the single mother of two.
It is impossible to prove we were damaged, so we should not have to prove that any copyright theft took place. It's wonderful logic and we look forward to this forming a cornerstone of law in future. After all, it's difficult to prove that Marie van Uitert has been brainwashing my cat in order to turn it into a killing machine, but - hey - that need not be a problem any more, need it?