A judge has ruled the copyright on the classic "Happy Birthday" song to be invalid, putting a halt to a music publishing company's royalty collections.

According to The Hollywood Reporter, U.S. District Judge George King came to the decision after determining that Summy Co. never obtained the rights to the song's lyrics.

"Because Summy Co. never acquired the rights to the 'Happy Birthday' lyrics, [the] defendants, as Summy Co's purported successors-in-interest, do not own a valid copyright in the Happy Birthday lyrics," wrote King in an online statement.

It may seem inconceivable that "Happy Birthday to You," the iconic tune played at countless birthday celebrations every year, was not public domain until this latest ruling. However the Warner/Chappell Music company has been enforcing a copyright claim on the song for decades.

The song originated in the 19th century, when kindergarten teacher Patty Smith Hill and her sister Mildred created the tune for schoolchildren.

The Hill sisters later assigned the rights to a publishing company owned by Clayton Summy. In 1935 the company registered a copyright for musical arrangement of the song. No specification was made for the lyrics.

"Defendants ask us to find that the Hill sisters eventually gave Summy Co. the rights in the lyrics to exploit and protect, but this assertion has no support in the record," wrote King in the judgment. "The Hill sisters gave Summy Co. the rights to the melody, and the rights to piano arrangements based on the melody, but never any rights to the lyrics."

The ruling came in response to a 2013 lawsuit by film director Jennifer Nelson, who was told to pay $1,500 for the rights to use the song in her documentary. Warner/Chappell has reportedly made over $2 million a year from the copyright, though the plaintiffs are now seeking a return on these fees.

"Happy Birthday is finally free after 80 years," plaintiff attorney Randall Newman said. "Finally, the charade is over. It's unbelievable."