https://arstechnica.com/tech-policy/2023/06/lawyers-have-real-bad-day-in-court-after-citing-fake-cases-made-up-by-chatgpt/

A federal judge tossed a lawsuit and issued a $5,000 fine to the plaintiff's lawyers after they used ChatGPT to research court filings that cited six fake cases invented by the artificial intelligence tool made by OpenAI.

Lawyers Steven Schwartz and Peter LoDuca of the firm Levidow, Levidow, & Oberman "abandoned their responsibilities when they submitted non-existent judicial opinions with fake quotes and citations created by the artificial intelligence tool ChatGPT, then continued to stand by the fake opinions after judicial orders called their existence into question," US District Judge Kevin Castel wrote in an order yesterday. The lawyers, Castel wrote, "advocated for the fake cases and legal arguments" even "after being informed by their adversary's submission that their citations were non-existent and could not be found."