Music Publishers v. Anthropic

Two cases, one set of publishers

Music publishers — Universal Music Publishing Group, Concord Music Group and ABKCO among them — sued Anthropic in October 2023, alleging Claude was trained on lyrics to roughly 500 works and would reproduce them, or close paraphrases, on request. The case moved from a Nashville filing to the Northern District of California in 2024.

In January 2025, Anthropic stipulated to maintaining output guardrails against reproducing the publishers’ lyrics. Two months later, the court denied a preliminary injunction against training use itself, finding the publishers had not shown irreparable harm — while allowing further evidence-gathering to continue.

How discovery in a different case blew the number up

The original suit stayed a contained, roughly 500-work dispute for two years. Then, in January 2026, the same publishers filed a second, far larger suit — reported at approximately $3 billion, covering more than 20,000 musical works, and alleging Anthropic sourced them from pirated shadow libraries rather than lawful acquisition.

The escalation traces directly to the unrelated Bartz v. Anthropic books litigation, where discovery surfaced that Anthropic had downloaded roughly seven million books from pirate libraries LibGen and PiLiMi. Those books, the publishers now allege, contained songbooks and lyrics — and evidence from that record, including allegations that co-founder Benjamin Mann personally used BitTorrent to pull down millions of pirated files, is now central to the new complaint.

The original case heads toward summary judgment

Fact and expert discovery closed in the original lyrics suit, and on March 23, 2026 the publishers moved for partial summary judgment, arguing — in a 47-page statement citing 218 supposedly undisputed facts drawn from depositions, internal documents and Anthropic’s own admissions — that the infringement evidence is overwhelming and that fair use does not excuse it.

A summary-judgment hearing is scheduled for October 21, 2026 before Judge Eumi Lee, who will decide whether to grant partial summary judgment to the publishers on copyright infringement or, alternatively, summary judgment to Anthropic on fair use and non-infringement.

“The evidence in this case is overwhelming.”— Publishers’ motion for partial summary judgment, N.D. Cal., March 23, 2026

Anthropic tried to slow the follow-on case, and lost

Anthropic asked the court to stay the $3 billion follow-on case until the original suit resolved — a reasonable-sounding request given the overlapping subject matter. The court refused on April 24, 2026, meaning the two cases now proceed on parallel tracks rather than sequentially. Anthropic’s response in the follow-on case is due August 3, 2026. Industry groups including the RIAA and NMPA have filed amicus support for the publishers in the original case.

What this means for licensing and chain of title

Lyrics are licensed text with an existing, well-understood market — publishers can point to what a legitimate mechanical or synchronization license already costs, which makes this a cleaner damages story than most scraping cases. That is exactly why the case matters beyond music: any text corpus that might contain licensed lyrical content, even incidentally, carries the same exposure.

The bigger lesson is procedural, and it should worry any data buyer relying on a vendor’s assurances. A contained dispute became a $3 billion claim because evidence from an entirely different lawsuit exposed how the underlying training corpus was assembled. Vendor diligence now has to account for discovery exhaust from other dockets, not just the deal in front of you — chain of title isn’t just what your contract says, it’s what a court in an unrelated case might later find.