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Large Legal Fictions: Profiling Legal Hallucinations in Large Language Models

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arxiv 2401.01301 v2 pith:SEEVKSX5 submitted 2024-01-02 cs.CL cs.AIcs.CY

Large Legal Fictions: Profiling Legal Hallucinations in Large Language Models

classification cs.CL cs.AIcs.CY
keywords legalhallucinationsllmsmodelslargealwayscasesevidence
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Do large language models (LLMs) know the law? These models are increasingly being used to augment legal practice, education, and research, yet their revolutionary potential is threatened by the presence of hallucinations -- textual output that is not consistent with legal facts. We present the first systematic evidence of these hallucinations, documenting LLMs' varying performance across jurisdictions, courts, time periods, and cases. Our work makes four key contributions. First, we develop a typology of legal hallucinations, providing a conceptual framework for future research in this area. Second, we find that legal hallucinations are alarmingly prevalent, occurring between 58% of the time with ChatGPT 4 and 88% with Llama 2, when these models are asked specific, verifiable questions about random federal court cases. Third, we illustrate that LLMs often fail to correct a user's incorrect legal assumptions in a contra-factual question setup. Fourth, we provide evidence that LLMs cannot always predict, or do not always know, when they are producing legal hallucinations. Taken together, our findings caution against the rapid and unsupervised integration of popular LLMs into legal tasks. Even experienced lawyers must remain wary of legal hallucinations, and the risks are highest for those who stand to benefit from LLMs the most -- pro se litigants or those without access to traditional legal resources.

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Forward citations

Cited by 8 Pith papers

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