Anyone who’s ever tried to record an old, obscure song and, despite extensive searching, couldn’t find the song’s owner in order to pay mechanicals, knows the Copyright Office allows the filing of a Notice Of Intent. An NOI basically says that you have tried to fulfill your legal responsibility. So, should the rights-holder show up, they’ll be paid, but you can’t be sued for your use of their song. Well, you just won’t believe how far Google, Pandora and Spotify have taken this concept. They’ve filed NOIs by the millions, seizing on any situation in which there's an imperfect match (even the slightest misspelling) with what’s filed at the Copyright Office, in order not to pay. Chris Castle gives a thorough explanation of this debacle in his MusicTechPolicy blog.