A federal judge in Mississippi has punished all four lawyers on opposing sides in a civil trial and canceled the proceedings after some of them, relying on artificial intelligence, cited fake legal cases in court filings.
Two of the lawyers have been barred for two years from appearing in the U.S. District Court for the Northern District of Mississippi for their conduct, while all four were removed from the case and fined.
The case stemmed from a 2023 breach of contract lawsuit over legal fees that Tom Withers III, a Louisiana lawyer, claimed he was never paid by the city of Aberdeen, Miss., connected to a solar power development project.
Mr. Withers was not one of the lawyers who was disciplined, but both attorneys who were representing him in the case, Kathleen M. Wilson and Shauncey Hunter Ridgeway, were punished, as well as two lawyers for the city, Kathryn Y. Williams and Mark McClinton.
In an order filed on Monday, Sharion Aycock, a senior U.S. District Court judge, wrote that the four lawyers had violated Rule 11 of the Federal Rules of Civil Procedure when they certified that the information in their filings was factual.
“This case presents the court with an unusual scenario — attorneys for both litigants engaged in similar sanctionable conduct,” Judge Aycock wrote.
The case is emblematic of the conundrum that many institutions are facing over the use of artificial intelligence for both research and written materials, including in the judicial system, the business world and academia.
In April, an elite Wall Street law firm apologized to a federal judge for submitting a court filing replete with errors created by artificial intelligence.
In the Mississippi case, the disciplinary actions were reported earlier by 404 Media and Robert Freund, a lawyer who tracks the misuse of A.I. in legal cases.
Both Ms. Wilson and Ms. Williams acknowledged during a hearing in January that they had not verified the authenticity of some of the cases they referred to in court filings, Judge Aycock noted.
Neither responded to a request for comment on Tuesday. Both were barred for two years by Judge Aycock, who fined Ms. Wilson $2,500 and Ms. Williams $3,500.
Each was granted temporary admission to participate in the case in Mississippi because they hold law licenses in other states (Louisiana and Texas).
Judge Aycock said Ms. Wilson told her that she had used First Drafts, an A.I.-powered program for drafting legal documents, while writing a motion that contained two citations to nonexistent cases, which are known as hallucinatory citations.
When confronted about those falsehoods, the judge said, Ms. Wilson claimed she was “unaware that A.I. could produce hallucinated cases and explained that she did not even know what a hallucinated case was.”
In an email on Wednesday, First Drafts described the disciplinary actions imposed on the lawyers as “unfortunate” and said that its platform advises users that “all A.I.-generated text and proposed citations must be independently verified.”
The company added: “While A.I. is a powerful tool for accelerating the drafting process, it is not a substitute for lawyers and their professional judgment.”
Judge Aycock noted that Ms. Wilson was also disciplined in April by the U.S. Bankruptcy Court for the Western District of Louisiana for similar actions.
“Her continued A.I. misuse demonstrates an extreme dereliction of professional responsibility on her part,” the judge wrote.
Judge Aycock said Ms. Williams explained to her at the January hearing that her law firm did not use open-ended A.I. but had acquired software that relies on A.I. and was used for in-house research.
She used that A.I. tool when writing two separate filings that contained four fake cases, according to Judge Aycock, who said Ms. Williams acknowledged that the software included cases from several states, but not Mississippi.
In contrast to Ms. Wilson’s solo law practice, which did not have a policy governing the use of A.I., Ms. Williams’s firm requires lawyers to verify research, according to Judge Aycock.
“The court finds it particularly egregious that Williams, a partner and presumably a leader in her law firm, disregarded the A.I. policy by blindly relying on the A.I. research tool,” the judge wrote.
Christian & Small, the law firm that employs Ms. Ridgeway as a partner in its Jackson, Miss., office, said in an email on Wednesday that it could not discuss its representation of individual clients under the rules of professional conduct.
“We will continue to educate our team about the appropriate use of artificial intelligence tools when they can benefit our clients, and the absolute requirement that our lawyers verify all information in our filings is accurate and correct,” Greer B. Mallette, a managing partner for the firm, wrote in the email.
Mr. McClinton declined to comment.
Both Ms. Ridgeway and Mr. McClinton have law licenses in Mississippi and sponsored the temporary admission of Ms. Wilson and Ms. Williams to participate in the case.
Judge Aycock fined each of them $1,000 and ruled that both lawyers had also violated the civil procedure rules by signing their names to the court filings.
In a statement on Wednesday, Michelle A. Behnke, the president of the American Bar Association, noted that the institution had created a task force focused on artificial intelligence that published its findings in December 2025 and issued ethics guidance on the use of A.I. in 2024.
“While the A.B.A. does not address individual attorney discipline cases, we are seeing the challenges and complexities lawyers face in using A.I. in their work,” Ms. Behnke said. “Lawyers understand that generative A.I. outputs require scrutiny and oversight.”
The Mississippi Bar did not immediately respond to questions about the situation on Tuesday.
The breach of contract case had been scheduled to go to trial in March, but Judge Aycock canceled the proceedings and issued a stay in the case.