ChatGPT Hallucination Case: US Lawyer Fined USD 5,000 Over Fake Witness Testimony

ChatGPT has landed a US defense lawyer in trouble after AI-generated material containing fabricated police and witness testimony was included in a court filing, according to the New Mexico Supreme Court. Attorney Stephen Aarons was fined USD 5,000 and held in contempt after the court found that his filing contained false testimony attributed to entirely fabricated witnesses.

The case has renewed concerns over the risks of relying on artificial intelligence for legal research and court filings. The New Mexico Supreme Court said Aarons failed to properly verify the information generated with the help of ChatGPT and criticised his conduct in handling the appeal.

ChatGPT Hallucination Case: What Happened?

Aarons was representing Oscar Renee Sandoval in an appeal against his murder conviction. Sandoval, who pleaded not guilty to murdering his children, was convicted and sentenced to life in prison last year. Anthropic Claims Claude Was Used in Yemen Missile Plot, Russian-Chinese Cyber-Espionage Operations.

According to the court, Aarons' appeal filing included fabricated witness testimony and other information that did not appear in the actual trial record. Aarons told Reuters that he had used ChatGPT to summarise the trial proceedings after taking up Sandoval's appeal last year.

The lawyer said he did not realise the extent to which AI could "hallucinate" or generate false information. Aarons described the incident as an honest mistake and said it was a lesson for professionals using AI tools.

New Mexico Supreme Court Fines Lawyer

The New Mexico Supreme Court fined Aarons USD 5,000 and held him in contempt for failing to verify the accuracy of the material submitted to the court. The justices also said they would refer the attorney to the state's attorney disciplinary board for investigation. Anthropic Says Iran-Linked Operators Used Claude AI To Target US Naval Bases.

The court criticised Aarons' handling of the matter, saying he had demonstrated a lack of remorse and concern for his client. The case highlights the responsibility of lawyers to independently verify AI-generated information before using it in legal proceedings.

AI Hallucinations In Legal Cases

AI-generated errors in legal filings are not new. Lawyers in several cases have faced sanctions after submitting briefs containing fictitious case citations, incorrect quotations or fabricated legal authorities generated by AI tools.

However, the New Mexico case appears particularly serious because the filing allegedly included fabricated testimony from witnesses who did not exist. The incident underscores the potential consequences of treating AI-generated summaries as reliable substitutes for reviewing court records and transcripts.

Sandoval's appeal remains pending and was assigned to New Mexico public defender Kim Chavez Cook on September 2.

(The above story first appeared on LatestLY on Sep 11, 2026 08:37 PM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).