Simon Willison’s Weblog

AI Hallucination Cases (via) Damien Charlotin maintains this database of cases around the world where a legal decision has been made that confirms hallucinated content from generative AI was presented by a lawyer.

That's an important distinction: this isn't just cases where AI may have been used, it's cases where a lawyer was caught in the act and (usually) disciplined for it.

It's been two years since the first widely publicized incident of this, which I wrote about at the time in Lawyer cites fake cases invented by ChatGPT, judge is not amused. At the time I naively assumed:

I have a suspicion that this particular story is going to spread far and wide, and in doing so will hopefully inoculate a lot of lawyers and other professionals against making similar mistakes.

Damien's database has 116 cases from 12 different countries: United States, Israel, United Kingdom, Canada, Australia, Brazil, Netherlands, Italy, Ireland, Spain, South Africa, Trinidad & Tobago.

20 of those cases happened just this month, May 2025!

I get the impression that researching legal precedent is one of the most time-consuming parts of the job. I guess it's not surprising that increasing numbers of lawyers are returning to LLMs for this, even in the face of this mountain of cautionary stories.