CaseFacts: A Benchmark for Legal Fact-Checking and Precedent Retrieval

Akshith Reddy Putta, Jacob Devasier, Chengkai Li


Abstract
Automated Fact-Checking has largely focused on verifying general knowledge against static corpora, overlooking high-stakes domains like law where truth is evolving and technically complex. We introduce CaseFacts, a benchmark for verifying colloquial legal claims against U.S. Supreme Court precedents. Unlike existing resources that map formal texts to formal texts, CaseFacts challenges systems to bridge the semantic gap between layperson assertions and technical jurisprudence while accounting for temporal validity. The dataset consists of 6,294 claims categorized as Supported, Refuted, or Overruled. We construct this benchmark using a multi-stage pipeline that leverages Large Language Models (LLMs) to synthesize claims from expert case summaries, employing a novel semantic similarity heuristic to efficiently identify and verify complex legal overrulings. Experiments with state-of-the-art LLMs reveal that the task remains challenging; notably, augmenting models with unrestricted web search degrades performance compared to closed-book baselines due to the retrieval of noisy, non-authoritative precedents. We release CaseFacts to spur research into legal fact verification systems.
Anthology ID:
2026.acl-long.785
Volume:
Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers)
Month:
July
Year:
2026
Address:
San Diego, California, United States
Editors:
Maria Liakata, Viviane P. Moreira, Jiajun Zhang, David Jurgens
Venue:
ACL
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
17246–17265
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.785/
DOI:
Bibkey:
Cite (ACL):
Akshith Reddy Putta, Jacob Devasier, and Chengkai Li. 2026. CaseFacts: A Benchmark for Legal Fact-Checking and Precedent Retrieval. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 17246–17265, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
CaseFacts: A Benchmark for Legal Fact-Checking and Precedent Retrieval (Putta et al., ACL 2026)
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PDF:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.785.pdf
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