Anthropic illegally trained Claude with Stanford professors' books

Anthropic illegally scraped and pirated the work of over 10 Stanford professors to train its Claude models, a federal judge ruled in a May 2026 lawsuit. stanforddaily.com's report, by April Yu, was published at 2:46 a.m. on Oct. 27, 2026 and updated at 3:19 a.m. Anthropic previously trained Claude on illegally obtained texts from Tobias Wolff, Abraham Verghese, Chang-Rae Lee, Daniel Mason, Hayagreeva Rao, and Myra Strober.

This piece is for authors, publishers, and Stanford faculty who need the Claude training facts in one place. It covers Judge William Alsup's ruling in Bartz v. Anthropic, the opt-out lawsuit Cruz v. Anthropic, and the Authors Guild's work with Congress on a licensing law, including the guild's case against OpenAI and Microsoft.

Anthropic illegally trained Claude: what actually changed

Judge William Alsup blocked the piracy of work to train AI and ruled that Anthropic could no longer pirate books to create a permanent central library. He justified legal acquisition of books for Claude's LLMs as fair use. He compared AI training to humans reading, internalizing, and remembering a book's themes and style. "Like any reader aspiring to be a writer, Anthropic's LLMs trained upon works not to race ahead and replicate or supplant them — but to turn a hard corner and create something different," he wrote.

The $1.5 billion settlement went to authors and publishers of nearly 500,000 registered works. Tobias Wolff, professor emeritus of English and winner of the National Medal of Arts, and 27 other authors say the settlement is not enough. 10 of Wolff's publications had been used for AI training without permission. "To put me to work that way, without remittance, is a form of slave labor," Wolff said. "They're using my work without paying for it. As time goes on, they're going to make the lives of writers very difficult if there's no fruit to their labor."

Anthropic illegally trained Claude: how it works

Similar to the claims in Bartz, plaintiffs in Cruz v. Anthropic allege that Anthropic illegally downloaded, reproduced, and distributed their copyrighted books from shadow libraries such as LibGen and PiLiMi. They allege Anthropic broke the law by downloading the pirated files and storing them in a central library. That stored collection is the permanent central library Alsup ruled Anthropic could no longer create with pirated books. He justified the legal acquisition of books as fair use for training Claude's LLMs.

Paul Goldstein, a leading scholar in intellectual property at Stanford Law and one of the plaintiffs represented in the class action, wrote in an email to The Daily. "The essential problem … is what economists call 'transaction costs,'" Goldstein wrote. "Millions of individual copyrighted works may be copied in the course of any training incident, and it's simply impracticable for the platform to obtain licenses from the copyright owner of every — or, indeed, any — single work." One training incident can copy millions of copyrighted works.

Anthropic illegally trained Claude: why it matters now

The Authors Alliance calls Bartz v. Anthropic the largest copyright settlement involving an AI company. Tobias Wolff and English professor Chang-rae Lee opted out. In May 2026 they filed the separate non-class lawsuit Cruz v. Anthropic, seeking a jury trial for full statutory damages of up to $150,000 per infringed work, surpassing the approximate $3,000 of damages per work offered in the Bartz settlement. "Our agents didn't think the blanket lawsuit covered quite enough of the liability to us and are seeking redress in more particular ways," Wolff said.

"[The settlement] still gives Anthropic pretty free rein to roam through our literature and basically take what they think will be useful and profitable for them," Wolff said. If Wolff and his fellow authors are successful, they would gain a permanent injunction against Claude model training using their works. The Cruz plaintiffs allege the same illegal downloading, reproduction, and distribution described in Bartz. Bartz established the current rule for pirating books, while the legal future of mass scraping AI models used to train LLMs remains uncertain.

Anthropic illegally trained Claude: who is affected

Outside Bartz and Cruz, authors, visual artists, and news outlets, including The New York Times and Getty Images, have filed over 70 infringement lawsuits against AI companies. The Authors Guild is pursuing other lawsuits, including one against OpenAI and Microsoft, as part of a "multi-pronged approach to ensure that the law is clear that AI companies must license the books they use," according to Chief Executive Officer Mary Rasenberger. Some authors are waging these difficult legal battles to achieve a sense of credit for their work, outside of the settlement payment.

For Wolff, this support is critical for the next generation of writers. "I'm lucky that I'm able to have a life as a writer where I enjoy the profits of my work," Wolff said. "I worry much more about the young writers I've worked with at Stanford and elsewhere being able to do that in the face of these technological challenges, because they're very hard to grasp and to combat." Anthropic trained Claude on illegally obtained texts from Tobias Wolff, Abraham Verghese, Chang-Rae Lee, Daniel Mason, Hayagreeva Rao, and Myra Strober.

Anthropic illegally trained Claude: what to watch

The Authors Guild is working with Congress to create national legislation that will require licensing. "Licensing allows authors and publishers to be compensated and to require the use of filters that ensure their works do not appear in outputs unless separately licensed," Mary Rasenberger wrote in an email to The Daily. "The Guild is up for the challenge," Rasenberger wrote. "This is something we have been doing for 114 years, and the moment we are in today, while challenging, also presents opportunities for us to firmly realize our mission."

"Attribution … is very important to the vast majority of authors, and not just academic authors," Paul Goldstein wrote. "The great majority of countries have something called the 'moral right of attribution' on the books to ensure that authors are credited for their work," he wrote. "The U.S., alone among industrialized nations, has no such moral right, which is a terribly unfortunate situation for authors generally." Wolff said Stanford authors and AI companies must navigate a "foreign land," meeting at the intersection of creative rights and technological growth.