All hell has broken loose in a 25-year legal battle over the rights to Nina Simone’s music.

Sony Music has filed papers in a San Francisco federal court aiming to rescind a settlement agreement reached with the late singer’s estate and her former lawyer. Sony is seeking confirmation that it owns and has the right to exploit Simone’s master recordings, upon receiving information that its rights may be drastically limited.

Simone’s former husband, manager and producer, Andrew Stroud, had been a key player in the dispute until recently. Stroud was granted ownership of his former wife’s recordings upon their divorce in 1972, but passed away in 2012.

Another key player in the dispute is Steven Ames Brown, an attorney who represented Simone in the late 1980s and 1990s and brokered a deal where he would be assigned 40 percent of her rights to works he “recovered.”

Last October, Sony Music, Brown and the Simone estate participated in a settlement conference before a magistrate with the aim of resolving all disputes related to Simone’s recordings. All three parties reached an agreement at the conference, which Sony lawyers have done their best to keep private. Sony told a judge yesterday that if its competitors, artists and potential artists learn about the “atypical” deal then it would represent a “significant danger”.

Sony is attempting to seal or at least redact a document that reveals it agreed to pay $390,000 to Brown under the settlement, reverse $105,963 in producer costs for Simone, and change royalty rates for Simone recordings. In return, the Simone estate and Brown would quitclaim to Sony the rights to various Simone recordings. A long-form agreement was supposed to follow, but the deal has hit yet another snag.

The case was blown wide open last week when Sony came forward to submit cross claims in an action brought by Andrew Stroud’s law firm, which held many of Simone’s master recordings and didn’t know what to do with them. Stroud’s firm filed a complaint as an interpleader, naming everyone who has ever fought over Simone recordings as a defendant (including Warner Bros.).

In Sony’s cross claim, the recording giant describes why its settlement agreement should be rescinded. Sony claims it made the $390,000 payment to Brown, but that afterwards, the other parties did not hold up their end of the agreement. Sony claims that after the October settlement conference, Brown made “negotiations of the long-form agreement nearly impossible.”

Sony and Brown have disagreed over which works have been quitclaimed, with Sony upset that it has allegedly paid $390,000 for works “already owned by Sony Music.” On top of that, there’s the issue of an $84 million default judgment entered last December against Stroud’s estate in favour of the Simone estate.

“The Estate’s judgment against Stroud compensates the Estate for works that, under the terms agreed upon at the settlement conference, belong to Sony Music,” states Sony in its cross claim. “Aware that contesting the Estate’s motion to amend the judgment would likely destroy the parties’ ability to come to a long-form agreement, Sony Music instead raised the issue with Brown and the Estate out of court, and invited the parties to find a mutually agreeable way to remedy it.”

Sony continues, “In response, Brown took the position for the first time that he and the Estate had conveyed to Sony Music only the reproduction rights in the Simone masters, and no other rights. In particular, according to Brown, he and the Estate did not convey the rights to the physical embodiment of the recordings to Sony Music (nor, according to Brown, the public performance rights, the distribution rights, or any other of the ‘bundle of rights’ that constitutes copyright…”)

In case that isn’t clear, Sony spelled out its position explicitly:

“Sony Music literally cannot exploit the masters and pay Brown and the Estate royalties if the only rights it owns are the rights of reproduction,” it says.

Sony is attempting to rescind he settlement agreemeent and also sue Brown and the Simone estate for breaching the contract and failing to uphold the covenant of good faith and fair dealing. Sony is aiming to determine once and for all who exactly owns the rights to Simone’s legendary recordings, which include such iconic songs as ‘Strange Fruit’ and ‘Black is the Color’. [via The Hollywood Reporter]