LexRubric: A Rubric-Guided Diagnostic Benchmark for Open-Ended Legal Tasks

Yifan Chen, Haitao Li, Yiran HU, Kaisong Song, Jun Lin, Yueyue Wu, Qingyao Ai, Min Zhang, Yiqun Liu


Abstract
As large language models (LLMs) are increasingly applied to real-world legal tasks, evaluating the reliability of their open-ended legal responses has become essential. These tasks require context-sensitive answers and allow little room for error, motivating fine-grained and diagnostic evaluation that can identify specific sources of response quality failures. We introduce LexRubric, a rubric-based benchmark for evaluating open-ended Chinese legal tasks. LexRubric contains 649 instances from legal consultation and judicial examination, which reflect both everyday legal needs and professional legal reasoning and cover 14 legal scenarios. It further includes 12,337 expert-written atomic scoring criteria organized under a unified six-dimensional framework, enabling accurate evaluation and diagnostic analysis across tasks and evaluation dimensions. To validate the reliability of the evaluation, we test multiple judge models and compare model-based judgments with human judgments. We further evaluate 18 recent general and legal-domain LLMs on LexRubric. Results show that different models exhibit distinct capability profiles, and that open-ended legal tasks remain challenging for current LLMs. Data is available at: <https://github.com/foggpoy/LexRubric>.
Anthology ID:
2026.emnlp-main.792
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
18406–18422
Language:
URL:
https://aclanthology.org/2026.emnlp-main.792/
DOI:
Bibkey:
Cite (ACL):
Yifan Chen, Haitao Li, Yiran HU, Kaisong Song, Jun Lin, Yueyue Wu, Qingyao Ai, Min Zhang, and Yiqun Liu. 2026. LexRubric: A Rubric-Guided Diagnostic Benchmark for Open-Ended Legal Tasks. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 18406–18422, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
LexRubric: A Rubric-Guided Diagnostic Benchmark for Open-Ended Legal Tasks (Chen et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.792.pdf