Gaps or Hallucinations? Scrutinizing Machine-Generated Legal Analysis for Fine-grained Text Evaluations

Abe Hou, William Jurayj, Nils Holzenberger, Andrew Blair-Stanek, Benjamin Van Durme


Abstract
Large Language Models (LLMs) show promise as a writing aid for professionals performing legal analyses. However, LLMs can often hallucinate in this setting, in ways difficult to recognize by non-professionals and existing text evaluation metrics. In this work, we pose the question: when can machine-generated legal analysis be evaluated as acceptable? We introduce the neutral notion of gaps – as opposed to hallucinations in a strict erroneous sense – to refer to the difference between human-written and machine-generated legal analysis. Gaps do not always equate to invalid generation. Working with legal experts, we consider the CLERC generation task proposed in Hou et al. (2024b), leading to a taxonomy, a fine-grained detector for predicting gap categories, and an annotated dataset for automatic evaluation. Our best detector achieves 67% F1 score and 80% precision on the test set. Employing this detector as an automated metric on legal analysis generated by SOTA LLMs, we find around 80% contain hallucinations of different kinds.
Anthology ID:
2024.nllp-1.24
Volume:
Proceedings of the Natural Legal Language Processing Workshop 2024
Month:
November
Year:
2024
Address:
Miami, FL, USA
Editors:
Nikolaos Aletras, Ilias Chalkidis, Leslie Barrett, Cătălina Goanță, Daniel Preoțiuc-Pietro, Gerasimos Spanakis
Venue:
NLLP
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
280–302
Language:
URL:
https://aclanthology.org/2024.nllp-1.24
DOI:
Bibkey:
Cite (ACL):
Abe Hou, William Jurayj, Nils Holzenberger, Andrew Blair-Stanek, and Benjamin Van Durme. 2024. Gaps or Hallucinations? Scrutinizing Machine-Generated Legal Analysis for Fine-grained Text Evaluations. In Proceedings of the Natural Legal Language Processing Workshop 2024, pages 280–302, Miami, FL, USA. Association for Computational Linguistics.
Cite (Informal):
Gaps or Hallucinations? Scrutinizing Machine-Generated Legal Analysis for Fine-grained Text Evaluations (Hou et al., NLLP 2024)
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PDF:
https://aclanthology.org/2024.nllp-1.24.pdf