Dr Luke has filed a new libel lawsuit against Kesha's mother.
Dr Luke
The producer - whose real name is Lukasz Gottwald - originally filed a defamation suit against Pebe Sebert in 2014 but has added another after she "continued to publicly defame" him.
Luke's lawyer Christine Lepera told PEOPLE: "After we originally filed suit against Pebe Sebert, she continued to make outrageous, false and defamatory statements against Dr Luke in her widespread media campaign to damage and smear his name.
"Pebe Sebert's lawyers flat out refused to allow us to add those statements to the existing case or to toll the statute of limitations on them - so we've been compelled to file an additional action."
The new suit cites a 2016 Billboard interview with Pebe which Luke's team claims she used "as another opportunity to continue her public smear campaign and once again defame Gottwald with the same lies".
In the interview, Pebe again accused the producer of sexually assaulting her daughter.
Luke is seeking unspecified damages, but says that it would be "greatly in excess of the $75,000 jurisdictional minimum," according to The Wrap.
Pebe's lawyer told Pitchfork: "This marks Dr Luke's second effort to sue a mother for publicly supporting and believing her daughter about being raped. It's also a transparent attempt to delay the trial of these issues. Mrs Sebert looks forward to presenting her case to a jury as soon as possible. When the evidence is made public, she expects the jury will conclude that all of her statements have been justified."
Pebe has previously launched her own suit against the producer, who she claims caused her to suffer post-traumatic stress disorder (PTSD).
Kesha originally filed legal documents seeking to have her contract with the producer dissolved after accusing him of sexually, physically, verbally and emotionally abusing her for almost a decade.
In response to her lawsuit, which was filed in October 2014, Luke filed a counter-suit against the 'Die Young' hitmaker, accusing her of defamation.
Kesha is contractually bound to make three more albums with Dr Luke and his Kemosabe Records label, which is owned by Sony, and can't record any more music until she is released from it.