President Trump’s onetime personal lawyer and fixer, Michael Cohen, says he unwittingly passed along to his attorney bogus artificial intelligence-generated legal case citations he got online before they were submitted to a judge.

Cohen made the admission in a court filing unsealed Friday at Manhattan federal court after a judge earlier this month asked a lawyer to explain how court rulings that do not exist were cited in a motion submitted on Cohen’s behalf. Judge Jesse Furman had also asked what role, if any, Cohen played in drafting the motion.

The AI-generated cases were cited as part of written arguments attorney David M. Schwartz made to try to bring an early end to Cohen’s court supervision after he served more than a year behind bars. Cohen had pleaded guilty in 2018 to tax evasion, campaign finance charges, and lying to Congress, saying Mr. Trump directed him to arrange the payment of hush money to a porn actor and to a former Playboy model to fend off damage to his 2016 presidential bid.

Cohen, who was disbarred five years ago, said in a declaration submitted to the judge on Thursday that he found the citations by doing research through Google Bard and was unaware that the service could generate nonexistent cases. He said he uses the internet for research because he no longer has access to formal legal-research sources.

“As a non-lawyer, I have not kept up with emerging trends (and related risks) in legal technology and did not realize that Google Bard was a generative text service that, like Chat-GPT, could show citations and descriptions that looked real but actually were not,” Cohen said. “Instead, I understood it to be a super-charged search engine and had repeatedly used it in other contexts to (successfully) find accurate information online.”

Google rolled out Bard earlier this year as an answer to ChatGPT, which Microsoft has been integrating into its Bing search engine. The tools can quickly generate text based off prompts from a user, but have a tendency to make things up, also known as “hallucinations.”

Cohen blamed Mr. Schwartz, his lawyer and longtime friend, for failing to check the validity of his citations before submitting them to the judge, though he asked that the judge dispense mercy toward Mr. Schwartz, calling his failure to check the citations an “honest mistake” and “a product of inadvertence, not any intent to deceive.”

In a declaration filed with the court, Mr. Schwartz said he thought drafts of the papers to be submitted to the judge to dissolve Cohen’s probation early were reviewed by a former federal prosecutor now in private practice who also represents Cohen, E. Danya Perry. He said he never reviewed what he thought was another attorney’s research.

Ms. Perry, who discovered that the cited cases were bogus after seeing the court filing, said Mr. Schwartz’s claim that he came to “believe” that the citations came from Ms. Perry were “incorrect and I believe, far-fetched, as I had no involvement in any back-and-forth — not directly with Mr. Schwartz or his paralegal and not even indirectly through Mr. Cohen.”

When she learned of them, Ms. Perry reported the false case citations to the judge and federal prosecutors.

In her submission to the judge, Ms. Perry wrote, “Mr. Cohen engaged in no misconduct and should not suffer any collateral damage from Mr. Schwartz’s misstep.”

In discussing possible sanctions earlier this month, the judge noted that it was the second time this year that a judge at Manhattan federal court has confronted lawyers over fake citations generated by artificial intelligence. Two lawyers in an unrelated case were fined $5,000 for citing bogus cases that were invented by ChatGPT, the AI-powered chatbot.

In entering the 2018 guilty plea, Cohen did not name the two women who received hush money or even Mr. Trump, recounting instead that he worked with an “unnamed candidate” to influence the 2016 election. But the amounts and the dates lined up with $130,000 paid to porn actor Stormy Daniels and $150,000 that went to Playboy Playmate Karen McDougal to buy their silence in the weeks and months leading up to the presidential election, which Mr. Trump, a Republican, won over Secretary Clinton, a Democrat. Ms. Daniels and Ms. McDougal claimed to have had affairs with Mr. Trump, which he denied.

Earlier this year, Mr. Trump pleaded not guilty in New York state court at Manhattan to 34 felony charges alleging that he falsified internal business records at his private company to cover up his involvement in the payouts.

After his arrest, Mr. Trump said in a speech, “This fake case was brought only to interfere with the upcoming 2024 election and it should be dropped immediately.”

He has since pleaded not guilty to charges in three other criminal cases.

Associated Press