This is why lawyers have been getting in trouble using AI to review case law or (worse) to generate documents.

It creates citations and references that look close enough to be plausible but are just made up of thin air. CA passed a law explicitly requiring lawyers to review AI-generated documents that is now before the governor for signing (previously, lawyers were ethically expected to review documents submitted to the court or provided to clients but that doesn't have the same level of force as an explicit requirement).