The instantly recognisable song, "Happy Birthday to You", is at the centre of an unlikely legal battle as a production company attempts to challenge its copyright in a New York court.
Filmmaker Jennifer Nelson launched the legal action against Warner/Chappell Music after they reportedly ordered her to pay $1,500 (£955) for the use of the song in a documentary.
Nelson's company, Good Morning to You productions, accused the music company of "wrongfully and unlawfully" extracting "millions of dollars in unlawful licensing fees" by claiming to own the copyright.
They argue that the famous tune, which Warner/Chappell Music own the executive copyright to, should be "dedicated to public use and in the public domain", according to a lawsuit filed in a New York courthouse yesterday.
Ms Nelson and the company claim that even if there was a valid copyright, it would have expired in around 1921.
The company are seeking damages and restitution of all the license fees paid to the company for its use.
The popular song is cited as the most recognised song in the English language in the Guinness Book of World Records.
ITV News Correspondent Nina Nannar reports: