Music Publishers Sue Anthropic Over Torrented Songs in AI Training Data

Sony Music and Warner Chappell sued Anthropic, alleging it torrented songbooks to train Claude. The case turns on whether music was in the downloaded files.

30/08/2026 15:579 min read

On Friday, Sony Music Publishing and Warner Chappell Music filed a lawsuit against Anthropic. They allege that the company used BitTorrent to download songbooks and then incorporated them into Claude.

Anthropic has previously admitted to torrenting books, but has never acknowledged that music was included in those files. That is the basis of the copyright case.

Anthropic Music Lawsuit Explained

The complaint identifies two data sets, both sourced from shadow libraries that contained unlicensed copies of published works.

  • Approximately 5 million books were obtained from Library Genesis in June 2021.
  • A further 2 million came from Pirate Library Mirror in July 2022.

According to the publishers, sheet music and songbooks were part of those collections. Torrenting is not the only method mentioned in the filing.

The publishers also claim that Anthropic scraped lyrics from Musixmatch and LyricFind. Both platforms pay for the rights to display those lyrics.

“…one of the largest and most blatant ongoing thefts of intellectual property in history,” the opening line of the complaint reads.

Why Torrenting Is the Dangerous Part

A judge has already drawn this distinction once. Buying books and scanning them leaned toward fair use. Obtaining them from pirate sites did not. The same judge described those downloads in blunt terms.

“…straightforward piracy but at massive scale.”

That is why Anthropic’s destructive book scanning program survived court challenges, while its downloads ended in a settlement.

Torrenting falls on the wrong side of that line, and it introduces another problem. The software uploads as it downloads. Every copy taken is also a copy distributed.

Two of the four counts hinge on that point, both naming Dario Amodei and Benjamin Mann as individuals, not as employees. Companies settle. Individuals give depositions.

What It Could Cost

The publishers seek up to $150,000 for each song a jury determines was knowingly infringed. They claim hundreds of their songs were in those files. They estimate the broader training claim is in the tens of thousands.

Notably, however, Anthropic has defeated these publishers before. It overcame their attempt to block Claude’s training in a 2023 case over lyrics. Instead, it agreed to implement output guardrails.

Anthropic has not commented on this lawsuit.

Everything now depends on discovery. Did the songs reach Claude through a purchase or through a swarm?

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