Between a Rock and a Hard Place: The Tension Between Ethical Reasoning and Safety Alignment in LLMs

Shei Pern Chua, Zhen Leng Thai, Kai Jun Teh, Xiao Li, Qibing Ren, Xiaolin Hu


Abstract
Large Language Model safety alignment predominantly operates on a binary assumption that requests are either safe or unsafe. This classification proves insufficient when models encounter ethical dilemmas, where the capacity to reason through moral trade-offs creates a distinct attack surface. We formalize this vulnerability through TRIAL, a multi-turn red-teaming methodology that embeds harmful requests within ethical framings. TRIAL achieves consistently high attack success rates across models by exploiting the model’s own ethical reasoning to frame harmful actions as morally necessary compromises. Building on these insights, we introduce ERR (Ethical Reasoning Robustness), a defense framework that distinguishes between instrumental responses that enable harmful outcomes and explanatory responses that analyze ethical frameworks without endorsing harmful acts. ERR employs a Layer-Stratified Harm-Gated LoRA architecture, achieving robust defense against reasoning-based attacks while preserving model utility.
Anthology ID:
2026.acl-long.197
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:
4275–4310
Language:
URL:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.197/
DOI:
Bibkey:
Cite (ACL):
Shei Pern Chua, Zhen Leng Thai, Kai Jun Teh, Xiao Li, Qibing Ren, and Xiaolin Hu. 2026. Between a Rock and a Hard Place: The Tension Between Ethical Reasoning and Safety Alignment in LLMs. In Proceedings of the 64th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers), pages 4275–4310, San Diego, California, United States. Association for Computational Linguistics.
Cite (Informal):
Between a Rock and a Hard Place: The Tension Between Ethical Reasoning and Safety Alignment in LLMs (Chua et al., ACL 2026)
Copy Citation:
PDF:
https://preview.aclanthology.org/ingest-acl/2026.acl-long.197.pdf
Checklist:
 2026.acl-long.197.checklist.pdf