Meta scored a major victory in a copyright lawsuit on Wednesday when a federal judge ruled that the company did not violate the law when it trained its AI tools on 13 authors' books without permission. “The Court has no choice but to grant summary judgment to Meta on the plaintiffs’ claim that the company violated copyright law by training its models with their books,” wrote US District Court judge Vince Chhabria. He concluded that the plaintiffs did not present sufficient evidence that Meta’s use of their books was harmful. In 2023, a high-profile group of authors, including comedian Sarah Silverman and journalist Ta-Nehisi Coates, sued Meta, alleging that the tech behemoth had infringed on their copyright by training its large language models on their work. Kadrey v. Meta was one of the first cases of its kind; now there are dozens of similar AI copyright lawsuits winding through US courts. Chhabria had previously stressed that he planned to look carefully at whether the plaintiffs had enough evidence to show that Meta’s use of their work would hurt them financially. “The key question in virtually any case where a defendant has copied someone’s original work without permission is whether allowing people to engage in that sort of conduct would substantially diminish the market for the original,” he wrote in the judgment on Wednesday. This is the second major ruling in the AI copyright world this week; on Monday, US District Court judge William Alsup ruled that Anthropic’s use of copyrighted materials to train its own AI tools was legal. Though Alsup’s judgement handed Anthropic a win, it was a split decision, as the AI company will still have to face the plaintiffs in court for pirating their books. The plaintiffs’ lawyers in Kadrey v. Meta argued that Meta’s use of pirated materials was a major issue, but Chhabria did not focus on the claim like Alsup did, instead noting that the parties would have a Zoom conference to discuss how to handle the piracy claims. Chhabria further distinguished his stance from Alsup’s by stressing that Alsup was “brushing aside” the importance of market harm in his fair-use ruling by focusing on whether the use of the work was “transformative.” In copyright law, courts determine fair use in part by looking at whether the work that’s created based on copyrighted material is “transformative,” meaning it’s not a substitute for the original but rather something new. They also assess whether the new work causes “market harm,” or hurts the original rights holder financially. “It’s notable that he disagreed, sharply but respectfully, with Judge Alsup on the market dilution theory,” says James Grimmelmann, a professor of digital and internet law at Cornell University. Other legal experts highlighted Chhabria’s focus on market harm, too, noting that it could shape how future AI copyright cases are argued. “We haven't seen the last of this novel market dilution theory,” says Cardozo Law professor Jacob Noti-Victor. “That might change the game in the other cases, or in future litigation.”