Filmmaker Jennifer Nelson had to pay $1,500 to have "Happy Birthday to You" sung in the movie she's making. The money went to Warner Music Group, a company that claims to own the copyright on the song. A copyright is the legal right to use or sell a creative product such as a song, a TV show, a book, or a work of art. Warner has claimed the copyright for "Happy Birthday to You" since 1988. "I never thought the song was owned by anyone," Nelson said in an e-mail to The New York Times. "I thought it belonged to everyone." Nelson's movie is a documentary -- a film that uses pictures and/or interviews with people to create a factual report of real-life events -- and is actually about the history of the "Happy Birthday" song itself. Two sisters named Mildred and Patty Hill wrote a song called "Good Morning to All" in 1893. Over a short period of time, people began to sing the words "happy birthday to you" in place of the original lyrics to the tune of the Hill sisters' song. A number of history experts say that there is no record of who actually wrote the "Happy Birthday to You" lyrics . Historians also say there is no way to know when the general public began singing the "Happy Birthday" song, but they believe it was being sung by the public long before it was printed and owned by a company. Nelson's lawyers say this piece of music's history proves that "Happy Birthday to You" belongs to everyone in the general public. That would mean Warner Music Group has no right to charge anyone a fee to sing the song in any setting. Experts estimate that Warner/ Chappell, the publishing division of the Warner Music Group, has made about $2 million a year from licensing fees for "Happy Birthday to You." Nelson's lawyers are asking a court in New York City to order Warner/Chappell to return fees they have collected over the past four years for use of the "Happy Birthday" song. According to Nelson's lawyers, to sing the "Happy Birthday" song, people   _  .
should pay the Hill sisters should pay Warner Music Group need not pay for any purpose need not pay except for commercial use