In 2019 a metal cart rolled down the aisle of an Avianca flight from El Salvador to New York and struck Roberto Mata on the knee. Mata retained two personal injury lawyers to sue the airline, resulting in a case that made legal precedent—but not for a reason Mata or his attorneys would have hoped for. Instead, the two lawyers achieved notoriety in 2023 when the judge in the case fined the pair $5,000 for citing six fictitious cases, invented by artificial intelligence software, in a brief to the court.
The punishment was the first of its kind and was widely reported in legal circles as a cautionary tale for lawyers about the risk of relying on AI. That cautionary tale has not been heeded. In the two years since the incident, there have been no fewer than 139 instances of legal briefs containing AI-invented citations—including over 30 this May alone. While many of these came from self-represented litigants, they also include briefs filed by prominent national law firms. And, in one instance, a judge struck expert testimony submitted by a data scientist from AI giant Anthropic—on the grounds it contained a “hallucination” created by Anthropic’s own software.
