EASTHAMPTON — Easthampton author Daniel Gilbert has filed a copyright infringement lawsuit against Anthropic, the San Francisco-based artificial intelligence company behind Claude, claiming it used his book without permission when it downloaded millions of pirated books five years ago.

Gilbert filed the lawsuit in U.S. District Court in Springfield in May, claiming Anthropic stole from the book he co-authored in 2007, “Hacking World of Warcraft,” a guide to one of the most popular early-2000s video games, “World of Warcraft.”

Gilbert wrote the book with James Whitehead II, with Wiley Publishing listed as the copyright holder, according to court records. Anthropic has until July 29 to respond to the complaint.

The violation, Gilbert claims, occurred in 2021 and 2022 when Anthropic downloaded millions of pirated books, including his, from online pirate libraries LibGen and PiLiMi, to train AI bots, according to the lawsuit.

Gilbert only became aware of the issue in December, when he was notified that his work was included in a $1.5 billion settlement. That settlement stemmed from Bartz v. Anthropic, a case in which a group of authors sued the company, resulting in payments of about $3,000 for each of the roughly 500,000 books covered by the claim — including Gilbert’s.

The lawsuit started with a trio of authors in 2024 — novelist Andrea Bartz and nonfiction writers Charles Graeber and Kirk Wallace Johnson. Other authors joined the suit, and a settlement with Anthropic was reached in September 2025.

U.S. District Judge William Alsup found that training AI chatbots on copyrighted books wasn’t illegal but that Anthropic wrongfully acquired millions of books through pirate websites that it “knew had been pirated.”

Gilbert, however, requested that his book be removed from the Bartz settlement since Anthropic did not claim any wrongdoing in the case.

“I opted out because I wanted the chance to pursue accountability. Anthropic is a public benefit corporation and I expect them to live up to that standard and take responsibility for their actions,” Gilbert wrote in an email to the Gazette.

Gilbert said there have been people in the past taken to court and “called thieves” for downloading “a few pirated songs.”

Another lawsuit was filed against Anthropic last month — Shakespeare v. Anthropic — by a group of 100 authors who opted out of the Bartz settlement, seeking up to $71.4 million in statutory damages. While other authors have banded together to file group claims, Gilbert has filed his individually.

“Anthropic downloaded millions of pirated books, including mine. The Bartz settlement offered a payment with no acknowledgment of wrongdoing and no apology,” Gilbert wrote.