Meta Platforms has lost a bid to block a group of U.S. authors from questioning Meta CEO Mark Zuckerberg in a lawsuit accusing the company of misusing copyrighted books to train its artificial intelligence systems.

Zuckerberg's deposition is justified based on evidence that he was directly involved in Meta's AI-training decisions, U.S. Magistrate Judge Thomas Hixson in San Francisco said on Tuesday.

The lawsuit was filed against Meta last year by a group of authors including comedian Sarah Silverman. It alleges that the company infringed their copyrights by using their books to train AI language models. The writers have also brought a similar, ongoing case against Microsoft-backed OpenAI.

U.S. District Judge Vince Chhabria, who is presiding over the Meta case, separately allowed prominent litigator David Boies and other attorneys from his firm Boies Schiller Flexner to join the authors' legal team on Tuesday.

Chhabria had criticised the authors' lead attorney Joseph Saveri about the handling of the case during a Friday conference, according to the court's docket, warning against proceeding without "a newly constituted team."

Saveri said in a statement on the Boies firm's addition that he "look forward to joining our collective expertise and experience to continue to prosecute this novel, important case to a successful conclusion."

He declined to comment on the Zuckerberg deposition.

Spokespeople and an attorney for Meta did not immediately respond to a request for comment on the orders on Wednesday.

Several groups of copyright owners including writers, visual artists and music publishers have sued major tech companies over the unauthorised use of their work to train generative AI systems. The companies have argued that their AI training is protected by the copyright doctrine of fair use, and that the lawsuits threaten the burgeoning AI industry.

Meta asked the court for an order barring the authors from deposing Zuckerberg in their case and said they lacked "any substantiation for their belief that Mr. Zuckerberg has any special knowledge of this dispute."

But Hixson said on Tuesday that the authors provided evidence that Zuckerberg was "the chief decision maker and policy setter for Meta's Generative AI branch and the development of the large language models at issue in this action."

The case is Kadrey v. Meta Platforms Inc, U.S. District Court for the Northern District of California, No. 3:23-cv-03417.

For the authors: Joseph Saveri of the Joseph Saveri Law Firm; Matthew Butterick; and David Boies of Boies Schiller & Flexner

For Meta: Bobby Ghajar of Cooley