This actually happened in 2023 when a lawyer in New York filed a brief in a federal case that cited six legal precedents that didn't exist. When the judge caught it and asked where these cases came from, the lawyer admitted he'd used ChatGPT to help research and the AI had fabricated the citations completely. He'd apparently just copied what the chatbot generated without verifying any of it against actual court records.
The wild part is how easy it was for this to slip through initially. ChatGPT is genuinely convincing at sounding authoritative - it'll confidently invent case names, docket numbers, and quotes that sound totally legitimate if you don't actually look them up. The lawyer didn't run basic verification checks, which... yeah, that's on him. You can't just feed an AI prompt into legal filings without fact-checking every single thing it produces. AI hallucinates constantly and doesn't actually "know" what it's talking about - it's pattern-matching based on training data.
It definitely raised alarm bells about how people were using these tools carelessly in high-stakes situations. Courts took it seriously enough that some judges started explicitly warning attorneys not to rely on AI for legal research without human verification. The case itself faced sanctions and it became a cautionary tale that bounced around legal circles for a while. It's less about AI being dangerous in courtrooms and more about people being reckless with tools they don't fully understand.