Last time I checked, they need to prove that the files your trading are in fact music files with respect to the filename.. For example, if I have a file named Eminem - Slim Shady.mp3 that Im sharing and its actually some other file that I renamed to disguise it, technically Im not sharing copyrighted material.. This better explains the point Im getting at: Lets say your going to your mothers house to bring her some oregano and you stick in a sandwich bag.. On the way cops stop you for speeding and notice the bag of oregano and arrest you for possession of marijuana (bear with me cause I know you can tell apart the two ).. They never test the oregano to determine if its actually marijuana so when you go to trial or arraignment, the judge throws the case out because theres lack of evidence to support the charge.. Burden of proof is on the prosecutor, in this case, the State.. Since the State could not prove that it was in fact marijuana, then we have reasonable doubt whether it is marijuana.. Sure it looks like an mp3 of an artist, but is it really? Can they prove that just by looking at the filenames? RIAA has the burden of proof, a file list of what your sharing is not enough to justify that your sharing copyrighted material..