I'm glad Blue Attitude has answered his post to his satisfaction. However, I feel this is a topic of interest to many others for exactly the same question. I know The Rolling Stones was sued for a song as also was Led Zeppelin and Ed Sheerhan. I believe these suits were more for riffs or melodies but I'm sure a judge somewhere could apply it to lyrics of any song that was successful. I also know the Marvin Gay Estate is pretty suit happy if they hear anything that resembles any of Marvin Gay music.