A French court on Friday ruled that "Bolero", one of the best-known classical music pieces in the world, was written by Maurice Ravel alone, a decision with major financial implications.
A court in Nanterre outside Paris rejected claims that "Bolero" was a collaborative work with Alexandre Benois, a celebrated Russian stage designer.
The work "consequently remains in the public domain", the court said in a statement.
Ravel's "Bolero" had its debut at the Paris Opera in 1928, where it was an immediate sensation.
He died 10 years later, and his heirs earned millions of dollars until the copyright on the work expired in 2016 and passed into public domain.
In France, copyright runs for 70 years after a composer's death, though additional years were added to make up for losses during World War II.
However, the heirs of Benois, a stage designer who worked on the original performance of "Bolero", insisted he should have been credited as a co-author and were demanding a share of the proceeds.
And because Benois died in 1960, that would put "Bolero" back under copyright until 2039.
"The music of the Bolero was created especially for the ballet" and should not be considered as a standalone piece of orchestra music, a lawyer for the Benois estate told a French court in February.
Ravel's estate supported the claim that it was a "collaborative work" with the Russian set-dresser, not least because it would start receiving copyright payments again.
The claimants have pointed to various documents that name Benois as a co-author of the music.
On the other side is France's Society of Authors, Composers and Music Publishers (Sacem), which has said the claim is based on a "historical fiction".
Sacem points to an official declaration signed by Ravel in 1929 identifying him as the sole author.
"This is a very well-argued decision, which took care to examine all the elements brought to the court's attention," Yvan Diringer, who represents Sacem, told AFP on Friday.
Sacem's defence team said the rights once generated "millions and millions of euros" every year, though this had fallen to around 135,000 ($145,000) euros annually between 2011 and 2016.
Gilles Vercken, a lawyer for the Ravel estate, said: "We are calmly analysing the decision before responding to the press."