Sony and Warner's music publishers sue Anthropic, and the sharpest fight is over how the data was allegedly obtained
Two of the world's largest music publishers have sued Anthropic, naming its founders personally, over allegations that Claude was built on pirated lyrics and sheet music. The case leans on an earlier ruling with a crucial split: training on copyrighted work may be fair use, but pirating it to get there may not.
Sony Music Publishing and Warner Chappell Music, the publishing arms that control musical compositions rather than recordings, sued Anthropic in the Northern District of California on 28 August 2026, naming co-founders Dario Amodei and Benjamin Mann individually. The complaint alleges Anthropic built its Claude models partly on lyrics and sheet music obtained by torrenting pirated "shadow libraries" and by scraping licensed lyric sites. Every allegation is unproven, and Anthropic says it disagrees and will defend itself. The case is built on a distinction from an earlier ruling: that training an AI on copyrighted work can be lawful fair use, while acquiring that work through piracy is not. The publishers seek statutory damages that observers have described as potentially reaching billions, though the complaint states no total figure.
The lawsuits over what went into AI training data have moved past the abstract, and the newest one names names. On 28 August 2026, two of the largest music publishers on earth filed suit against Anthropic, the maker of Claude, and did something most of the earlier AI copyright cases did not: they named the company's co-founders as personal defendants. The sharpest question in the case is not really whether training an AI on copyrighted work can be lawful. It is how Anthropic allegedly acquired the works in the first place. Here is the careful version, with the line between what is confirmed and what is merely alleged kept firmly in place.
Who is suing, and over what?
The plaintiffs are Sony Music Publishing (US) LLC and Warner Chappell Music, Inc. A point worth getting right: these are the music-publishing businesses, which control lyrics and compositions, not the record labels that control recordings. Much of the coverage loosely says "Sony Music" and "Warner Music," but the copyrights at issue are the songs as written. The filing is reported to include around 35 affiliated publisher entities in total, roughly 24 on the Sony side and 11 on the Warner Chappell side, which is the corporate family of imprints rather than 35 independent companies.
The defendants are Anthropic PBC and its co-founders Dario Amodei, the chief executive, and Benjamin Mann, both named individually. The case was filed in the US District Court for the Northern District of California and carries docket number 5:26-cv-09217.
What the lawsuit alleges
Everything in this section is an allegation from the complaint. None of it has been tested or proven in court.
The publishers describe what they call a "brazen campaign of illegally torrenting, scraping, and downloading copyrighted works," and, in their own characterisation, "one of the largest and most blatant ongoing thefts of intellectual property in history." Those are the plaintiffs' words, not established facts. The specific claims include:
- Torrenting shadow libraries. The complaint alleges Mann used BitTorrent in June 2021 to download at least 5 million pirated books from Library Genesis (LibGen), and that Anthropic employees later torrented at least another 2 million from the "Pirate Library Mirror" in July 2022, and that these collections contained copyrighted lyrics and sheet music.
- Scraping licensed sites and stripping credits. It alleges Anthropic also scraped lyrics from licensed services and removed copyright-management information, the song titles, songwriter credits and copyright notices attached to the works, which forms a separate claim under the Digital Millennium Copyright Act.
- Infringing outputs. It alleges Claude can reproduce copyrighted lyrics closely and was used to generate large volumes of AI-written lyrics that act as "harmful market substitutes" for the originals.
The suit brings four counts: direct infringement by torrenting, brought against all three defendants including both founders; contributory infringement by torrenting, aimed at Amodei and Mann personally; a broad direct-infringement count covering both the training on the allegedly pirated copies and Claude's outputs; and the copyright-management-information claim under the DMCA.
The earlier ruling that makes acquisition the pivotal question
To understand why this case targets how the data was obtained, you have to look at Bartz v. Anthropic, decided in the same Northern District of California by Judge William Alsup in June 2025. That ruling drew a line that now sits at the centre of the new suit:
- Training was allowed. The court held that using copyrighted books to train a large language model was "quintessentially transformative" and qualified as fair use.
- Piracy was not. The same court held that acquiring and keeping a permanent library of pirated copies was not fair use, describing the downloading as "straightforward piracy but at massive scale." Anthropic later settled that piracy exposure for 1.5 billion dollars in September 2025.
The Sony and Warner Chappell complaint is built closely on that split. Rather than re-fight whether training is fair use, it presses the part of Bartz that went against Anthropic, the acquisition, and adds two theories Bartz did not resolve: the alleged infringing outputs and the alleged removal of copyright-management information. The clean way to summarise its central thrust is the way the case is framed: training on the material may be defensible, but obtaining it through piracy is the alleged wrong. The outputs and copyright-information claims then widen the case beyond acquisition alone.
How much money is at stake?
The complaint seeks statutory damages of up to 150,000 dollars per work willfully infringed, plus up to 25,000 dollars per violation for the copyright-management-information claims, along with injunctive relief that includes the destruction of infringing copies. Notably, the complaint itself does not name a total dollar figure. With tens of thousands of compositions said to be at issue, and statutory damages that can run to 150,000 dollars each, the potential exposure has been widely described as reaching into the billions. That "billions" figure is arithmetic and press framing, not a total the complaint states or a court has determined. The complaint also argues that Anthropic's prior 1.5-billion-dollar settlement is too small to deter a company reportedly targeting a roughly 2-trillion-dollar valuation ahead of a projected October 2026 public offering, figures that are themselves reported and projected rather than confirmed.
What Anthropic says
Anthropic rejects the claims. A company spokesperson said, "We disagree with the publishers' claims and we intend to defend ourselves robustly in court." The company has previously pointed to the fair-use side of the Bartz ruling, the finding that training itself can be transformative, as support for its position. As with the allegations, its defence has not been tested; the case is at its earliest stage.
The bigger wave this joins
This is not a lone filing but the latest in a run of music-industry suits against Anthropic. A group of publishers led by Universal Music Publishing, Concord and ABKCO first sued in October 2023 over roughly 500 songs. A further suit in January 2026 covered more than 20,000 works. BMG filed in March 2026, and Round Hill Music filed in mid-August 2026, shortly before this one. By most counts, the Sony and Warner Chappell action is roughly the fifth music-copyright case Anthropic is facing, and it is brought by the same lead counsel, the firm Oppenheim and Zebrak, that filed the original Universal-led suit in 2023.
| Filing | When | Scope (as reported) |
|---|---|---|
| Universal, Concord, ABKCO | Oct 2023 | ~500 songs (the first music-lyrics case) |
| Second publisher suit | Jan 2026 | 20,000+ works |
| BMG | Mar 2026 | ~493 compositions |
| Round Hill Music | Aug 2026 | (mid-August filing) |
| Sony Music Publishing, Warner Chappell | 28 Aug 2026 | founders named; adds outputs and CMI claims |
A central question runs through all of them that the courts are only starting to answer: not simply whether AI models can learn from copyrighted work, but what rules govern how that work is collected in the first place. For more, see our full AI coverage.
Frequently asked questions
Who is suing Anthropic in the Sony and Warner case?
Sony Music Publishing and Warner Chappell Music, the two companies' music-publishing arms, which control lyrics and compositions. The filing is reported to include around 35 affiliated publisher entities in total. Anthropic and its co-founders Dario Amodei and Benjamin Mann are named as defendants.
What does the lawsuit allege Anthropic did?
It alleges, without these claims being proven, that Anthropic obtained copyrighted lyrics and sheet music by torrenting pirated "shadow libraries" such as LibGen and by scraping licensed lyric sites, that it removed copyright information, and that Claude can reproduce and substitute for copyrighted lyrics.
Didn't a court already say AI training is fair use?
In Bartz v. Anthropic (June 2025), a court held that training a model on copyrighted books was transformative fair use, but that acquiring a permanent library of pirated copies was not. This new suit targets the acquisition, and adds claims about outputs and copyright-management information.
How much could Anthropic have to pay?
The complaint seeks up to 150,000 dollars per infringed work and up to 25,000 dollars per copyright-management-information violation, plus injunctive relief. It states no total, but the potential exposure has been widely described as reaching billions. That figure is press-and-arithmetic framing, not something the complaint states or a court has found.
What has Anthropic said?
An Anthropic spokesperson said the company disagrees with the publishers' claims and intends to defend itself robustly in court, and it has pointed to the fair-use finding in the Bartz ruling. The case is at an early stage and none of the allegations have been tested.
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