Beyond Case-Level Similarity: Multi-Defendant Legal Case Retrieval via Individual-Aware Reasoning

Yi Yang, Ruize Ma, Yi Feng, Chuanyi Li, Vincent Ng


Abstract
Legal Case Retrieval (LCR) aims to identify cases that are legally similar to a given query case. Existing research has largely recast LCR as the task of modeling the textual similarity between the query case and a historical case. While this approach can handle single-defendant cases fairly easily, such surface-level matching proves insufficient for multi-defendant cases, which typically requires modeling and aligning defendants’ roles and judgment outcomes in different cases. To address the challenges associated with Multi-defendant LCR (Multi-LCR), we (1) present Multi-ELAM and Multi-LeCaRDv2, two multi-defendant datasets we create by enriching widely used benchmarks with defendant-level annotations, and (2) introduce a novel role- and judgment-aware framework for Multi-LCR. Experimental results show that our approach outperforms state-of-the-art baselines, highlighting its effectiveness for Multi-LCR.
Anthology ID:
2026.emnlp-main.1918
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:
43688–43713
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1918/
DOI:
Bibkey:
Cite (ACL):
Yi Yang, Ruize Ma, Yi Feng, Chuanyi Li, and Vincent Ng. 2026. Beyond Case-Level Similarity: Multi-Defendant Legal Case Retrieval via Individual-Aware Reasoning. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 43688–43713, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Beyond Case-Level Similarity: Multi-Defendant Legal Case Retrieval via Individual-Aware Reasoning (Yang et al., EMNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.emnlp-main.1918.pdf