New Mexico's supreme court has fined and held in contempt a defence lawyer, Stephen Aarons, after he submitted a murder appeal brief containing police testimony and witnesses fabricated by ChatGPT. The case adds to a growing list of instances in which lawyers have been disciplined for filing AI-generated court documents without verifying their accuracy, but is notable for including fabricated witness testimony rather than merely invented case citations, raising fresh concerns about AI use in the legal profession.

The court fined Aarons, a private attorney in Santa Fe, $5,000 and said it would refer him to an attorney disciplinary board, criticising him for showing "a lack of remorse and a lack of concern for his client". Aarons said he had used ChatGPT to summarise trial proceedings while appealing the conviction of Oscar Renee Sandoval, who was jailed for life last year for murdering the mother of his children, and had not grasped how readily the tool could "hallucinate" facts, including fictional details about the shooter's clothing. At an August hearing, Justice Shannon Bacon voiced disbelief at his unfamiliarity with AI's known flaws, while Aarons called it "an honest mistake" and "a lesson learned". The appeal remains pending under a newly assigned public defender.