Better Call CLAUSE: A Discrepancy Benchmark for Auditing LLMs Legal Reasoning Capabilities

Manan Roy Choudhury, Adithya Chandramouli, Mannan Anand, Vivek Gupta


Abstract
The rapid integration of large language models (LLMs) into high-stakes legal work has exposed a critical gap: no benchmark exists to systematically stress-test their reliability against the nuanced, adversarial, and often subtle flaws present in real-world contracts. To address this, we introduce CLAUSE, a first-of-its-kind benchmark designed to evaluate the fragility of an LLM’s legal reasoning. We study the capabilities of LLMs to detect and reason about fine-grained discrepancies by producing over 7500 real-world perturbed contracts from foundational datasets like CUAD and ContractNLI. Our novel, persona-driven pipeline generates 10 distinct anomaly categories, which are then validated against official statutes using a Retrieval-Augmented Generation (RAG) system to ensure legal fidelity. We use CLAUSE to evaluate leading LLMs’ ability to detect embedded legal flaws and explain their significance. Our analysis shows a key weakness: these models often miss subtle errors and struggle even more to justify them legally. Our work outlines a path to identify and correct such reasoning failures in legal AI.
Anthology ID:
2026.findings-eacl.305
Volume:
Findings of the Association for Computational Linguistics: EACL 2026
Month:
March
Year:
2026
Address:
Rabat, Morocco
Editors:
Vera Demberg, Kentaro Inui, Lluís Marquez
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
5776–5818
Language:
URL:
https://preview.aclanthology.org/ingest-eacl/2026.findings-eacl.305/
DOI:
Bibkey:
Cite (ACL):
Manan Roy Choudhury, Adithya Chandramouli, Mannan Anand, and Vivek Gupta. 2026. Better Call CLAUSE: A Discrepancy Benchmark for Auditing LLMs Legal Reasoning Capabilities. In Findings of the Association for Computational Linguistics: EACL 2026, pages 5776–5818, Rabat, Morocco. Association for Computational Linguistics.
Cite (Informal):
Better Call CLAUSE: A Discrepancy Benchmark for Auditing LLMs Legal Reasoning Capabilities (Choudhury et al., Findings 2026)
Copy Citation:
PDF:
https://preview.aclanthology.org/ingest-eacl/2026.findings-eacl.305.pdf
Checklist:
 2026.findings-eacl.305.checklist.pdf