A filmmaker is suing to put the song "Happy Birthday to You" in the public domain, which would make it free to use, reports The New York Times.

Warner/Chappell Music, the publishing division of Warner Music Group, owns the rights to the song, which is thought to be the most performed song in the world.

The lawsuit comes from filmmaker Jennifer Nelson, who was producing a documentary about the song, tentatively called "Happy Birthday." She wanted to include a performance of the song, but was told she would have to pay $1,500 and enter into a licensing agreement with Warner/Chappell to do so.

"Before I began my filmmaking career, I never thought the song was owned by anyone. I thought it belonged to everyone," Nelson said in an email.

A spokesman for the music company declined to comment.

The lawsuit points out that in the late 1800s, two sisters wrote a song with the same tune, but with a different title ("Good Morning to All.") One of Nelson’s attorneys said that "Happy Birthday to You" is "just a public adaptation" of the original song.

"It’s a song created by the public, it belongs to the public, and it needs to go back to the public,” the attorney, Mark C. Rifkin, said.

Robert Brauneis, a professor at the George Washington University Law School who has studied the copyright issues around the song, told the newspaper that he believes the song is in the public domain.

He added that a successful legal challenge "might be a model for challenges to other songs.”