The attorneys ended up making use of fictitious or so-called AI-hallucinated legal precedents and got caught by the opposing side and the judge for providing falsities to the court.

Source: https://www.forbes.com/sites/lanceeliot/2023/07/01/transforming-generative-ai-into-domain-savviness-via-in-context-learning-and-a-dash-of-data-engineering-seems-promising-says-ai-ethics-and-ai-law/