A defence attorney in the US state of New Mexico has been fined $5,000 and held in contempt by the state's Supreme Court after submitting an appeal brief in a murder case that contained fabricated witnesses and invented police testimony generated by the AI tool ChatGPT. Lawyer Stephen Aarons, who was handling the appeal of a man convicted of murder and sentenced to life in prison, told the court he had used ChatGPT to summarise trial proceedings without realising the extent to which the technology could "hallucinate" false information. The court, which described Aarons as showing "a lack of remorse and a lack of concern for his client", has referred him to an attorney disciplinary board — the latest in a growing series of cases in which judges across the United States have sanctioned lawyers for filing AI-generated documents without adequate verification.