Anyone who has a pulse has followed the RIAA lawsuit saga over the past several years, with the RIAA suing various customers, also called litigants, over illegal file-sharing practices. The chief tool they have used is a company that closely monitors Kazza file share folders and takes snapshots of users' 'sharing folders' in order to present evidence against them at lawsuit hearings - if it even gets that far. To-date, many cases have been settled out of court, but some have gone to trial and a recent series of rulings has gone both ways for the RIAA.
Discuss "Judge to RIAA: You Have Burden of Proof" here. Read the article.
I think the judge made a wise ruling. Intent has long been an important part of the criminal legal system. Civil cases live by a different set of standards, but in a situation like what the RIAA is trying to accomplish, I think this makes sense. Simply have a folder of music that "can" be publicly accessed by others, on it's own doesn't prove that the poster put it there solely for the purpose of illegal copyright infringement and distribution, regardless of what we all know to be true.