Sony Music Publishing and Warner Chappell Music sued Anthropic and two of its co-founders on August 28, 2026, alleging that tens of thousands of copyrighted musical compositions were copied to train the company’s Claude AI models. The complaint, filed in the US District Court for the Northern District of California, names Chief Executive Officer Dario Amodei and co-founder Benjamin Mann as individual defendants alongside the company.
The plaintiffs, a group of publishing entities filing collectively as the Music Publishers, describe the conduct at issue as “one of the largest and most blatant ongoing thefts of intellectual property in history.” Songs named in the filing include “Ain’t No Mountain High Enough,” “All I Want for Christmas is You,” “Eye of the Tiger,” “Livin’ On a Prayer,” “September,” “Hallelujah,” and Taylor Swift’s “Paper Rings.” The publishers are demanding a jury trial.
The Four Counts
The complaint brings four claims. The first alleges direct copyright infringement through torrenting against all three defendants. The second charges Amodei and Mann personally with contributory infringement for directing and approving the torrenting activity. The third and fourth counts, brought against Anthropic alone, allege direct infringement through scraping, downloading, destructive scanning, model training, and AI outputs, plus removal or alteration of copyright management information, the identifying data such as song titles, songwriter names, and copyright notices that federal law protects.
According to the complaint, Mann used the BitTorrent protocol in June 2021 to download at least five million pirated books from Library Genesis, known as LibGen, and Anthropic employees torrented at least two million more from a successor site called Pirate Library Mirror in July 2022. The publishers allege those hauls included hundreds of songbooks and sheet-music collections containing their compositions, and that Amodei expressly authorized the downloads. Because BitTorrent users upload pieces of files to others while downloading, the complaint argues each torrent also violated the publishers’ exclusive right of distribution.
Beyond torrenting, the publishers allege Anthropic scraped lyrics from licensed lyric websites including MusixMatch and LyricFind in violation of those sites’ terms, ran a “destructive scanning” operation that digitized millions of second-hand physical books before destroying them, and drew on third-party datasets including Common Crawl, The Pile, and Books3. The complaint states the publishers have never licensed Anthropic to use their works in any of these ways.
Training, Outputs, and Guardrails
The filing describes how the allegedly unlicensed lyrics move through Anthropic’s development process. When Anthropic assembles a training corpus, the complaint says, engineers “clean” the text with extraction tools that strip out copyright notices and owner names while leaving the expressive content, a process the publishers characterize as deliberate concealment. The complaint alleges Claude models then memorize lyrics during training and can reproduce them verbatim or near-verbatim in response to user prompts, as well as generate derivatives “in the style of” represented songwriters.
The publishers acknowledge that Anthropic added guardrails intended to stop Claude from reproducing copyrighted text after earlier litigation, but allege those measures are easily circumvented by simply re-prompting the model. The complaint further argues that Claude’s ability to write new lyrics creates market substitutes that compete with the publishers’ catalogs and dilute the streaming royalty pools from which publishers and songwriters are paid.
Reliance on the Bartz Findings
Much of the complaint’s factual foundation comes from Bartz v. Anthropic, the authors’ class action in the same district, where the court found Anthropic had torrented millions of pirated books and described the conduct as “straightforward piracy but at massive scale.” Anthropic settled that case in September 2025 for $1.5 billion. The new filing quotes internal Anthropic material unsealed in Bartz, including Mann’s description of LibGen as “sketchy AF,” an Anthropic archive team’s characterization of the site as a “blatant violation of copyright,” and a 2024 planning document about the scanning operation stating, “We don’t want it to be known that we are working on this.”
“Dr. Amodei and Mr. Mann are personally liable for their respective roles in this illegal torrenting of pirated copies of Music Publishers’ works from LibGen and PiLiMi,” the complaint states.
Damages and Demands
The publishers seek statutory damages of up to $150,000 per work infringed where infringement is found willful, and up to $25,000 per violation for removal or alteration of copyright management information. They also ask the court to order Anthropic to destroy all infringing copies of their works under court supervision and to provide an accounting of its training data, training methods, and the specific lyrics and other copyrighted works used to train its models.
The publishers state in the filing that they recognize the potential of ethical AI technology and have entered licenses permitting authorized uses of their compositions by other AI companies. “Even the most revolutionary of technologies must develop within the bounds of the law, and Anthropic’s Claude models are no different,” the complaint reads. The publishers are represented by Oppenheim + Zebrak and Pryor Cashman. Anthropic had not publicly responded to the suit as of its filing date.