Video game company Valve Corp. has told a Washington federal court that a patent licensing company's filings seeking to exclude Valve's experts contained quotes and case citations that were nonexistent, suggesting the filings may have been made using artificial intelligence.

In a Monday response to motions to exclude its experts, Valve said defendants in the case — including Leigh Rothschild — "cite cases that do not exist" and that they "rely on case quotations that do not exist."

Valve said it was "concerned defendants improperly used artificial intelligence in the drafting process," and because of the allegedly fabricated quotes and citation issues, the court should ignore the exclusion bids.

"Defendants also misrepresent the import of the 'real' cases they cite, only offer conclusory assertions in support of their motions, and barely cite any actual material from the experts' reports," Valve said. "Contrary to defendants' arguments, Valve's experts provide specialized knowledge that will help the jury and court, and they will not instruct the jury on the law or opine on legal issues."

Valve, which is based in Bellevue, Washington, and publishes popular video game titles and sells them on its Steam online platform, launched the suit seeking a declaratory judgment in July 2023 to stop the defendants from making "bad faith" infringement claims over U.S. Patent No. 8,856,221. The suit alleged the defendants are pursuing bogus patent infringement claims against Valve, in violation of Washington state's anti-troll laws.

On Oct. 30, Valve asked for sanctions against Rothschild, alleging he failed initially to answer requests for information about the relationship between him and his corporate entities and responded the day prior only under "the looming threat" of the sanctions bid.

Rothschild's "entire business model" is to use "shell plaintiffs to protect Rothschild from personal liability," Valve said in the motion for sanctions. It asked the court to find that Rothschild himself is the alter ego of fellow defendants Patent Asset Management, Display Technologies and Rothschild Broadcast Distribution Systems, and that Patent Asset Management is the alter ego of Display Technologies and Rothschild Broadcast Distribution Systems.

In a separate suit, Rothschild has sued Baker Botts LLP intellectual property litigator Rachael Lamkin — who is not involved in the Valve suit — and Starbucks Corp. over Lamkin's comments in an October 2024 Bloomberg Law article, in which she's quoted as saying, "With Leigh Rothschild, we never get the money because the shells go bankrupt." The lawsuit claims defamation, intentional infliction of emotional distress, tortious interference with business relationships, and unfair competition.

Rothschild says that his companies are not shells and that he has never filed for bankruptcy. Lamkin filed a counterclaim in January, and her amended counterclaim filed in February slams the defamation suit as "sham litigation." Starbucks settled Rothschild's defamation suit in February.

Counsel for the parties did not immediately respond to requests for comment on Wednesday.

Valve is represented by Dario A. Machleidt, Kathleen R. Geyer, Christopher P. Damitio and David A. Reed of Kilpatrick Townsend & Stockton LLP.

The defendants are represented by Joseph J. Zito and René A. Vazquez of DNL Zito and Matthew J. Cunanan of DC Law Group.

The case is Valve Corp. v. Rothschild et al., case number 2:23-cv-01016, in the U.S. District Court for the Western District of Washington.