Michael Cohen Used Fake Cases Cited by A.I. to Seek an End to Court Supervision

Michael D. Cohen, the onetime fixer for former President Donald J. Trump, said in newly unsealed court papers that he had mistakenly given his lawyer bogus legal citations after the artificial intelligence program Google Bard cooked them up for him.

The fictitious citations were then used in a motion provided to a Manhattan federal judge. Mr. Cohen, who pleaded guilty in 2018 to campaign finance violations and served time in prison, had asked for an early end to court supervision of his case now that he was out of prison and had complied with the conditions of his release.

In a sworn declaration made public on Friday, Mr. Cohen explained that he had 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 ChatGPT, could show citations and descriptions that looked real but actually were not.”

He also said he did not realize that the lawyer filing the motion on his behalf, David M. Schwartz, “would drop the cases into his submission wholesale without even confirming that they existed.”

The revelation could have serious implications for the Manhattan criminal case against Mr. Trump, in which Mr. Cohen is expected to serve as the star witness. The former president’s lawyers have long attacked Mr. Cohen as a serial fabulist; now, they will have a brand-new example.

A spokeswoman for the Manhattan district attorney’s office declined to comment.

The new information about Mr. Cohen’s role in creating the bogus cases comes after the judge, Jesse M. Furman of Federal District Court, said in an order on Dec. 12 that he could not find any of the three decisions cited by Mr. Schwartz and ordered him to provide copies to the court.

If Mr. Schwartz could not produce the cases, Judge Furman said, the lawyer had to provide a sworn declaration that included “a thorough explanation of how the motion came to cite cases that do not exist and what role, if any, Mr. Cohen played in drafting or reviewing the motion before it was filed.”

Mr. Schwartz would also have to explain why he should not be sanctioned “for citing nonexistent cases to the court,” Judge Furman said in the Dec. 12 order.

The episode is the second this year in which lawyers in the Manhattan federal court have cited bogus court decisions created through the use of an artificial intelligence program.

Jonah E. Bromwich contributed reporting.