Analyzing Bias in False Refusal Behavior of Large Language Models for Hate Speech Detoxification

Shuzhou Yuan, Kyuri Im, Michael Färber


Abstract
While large language models (LLMs) have increasingly been applied to hate speech detoxification, the prompts often trigger safety alerts, causing LLMs to refuse the task. In this study, we systematically investigate false refusal behavior in hate speech detoxification and analyze the contextual and linguistic biases that trigger such refusals. We evaluate nine LLMs on both English and multilingual datasets, our results show that LLMs disproportionately refuse inputs with higher semantic toxicity and those targeting specific groups, particularly nationality, religion, and political ideology. Although multilingual datasets exhibit lower overall false refusal rates than English datasets, models still display systematic, language-dependent biases toward certain targets. Based on these findings, we propose a simple cross-translation strategy, translating English hate speech into Chinese for detoxification and back, which substantially reduces false refusals while preserving the original content, providing an effective and lightweight mitigation approach.
Anthology ID:
2026.findings-emnlp.319
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
6741–6769
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.319/
DOI:
Bibkey:
Cite (ACL):
Shuzhou Yuan, Kyuri Im, and Michael Färber. 2026. Analyzing Bias in False Refusal Behavior of Large Language Models for Hate Speech Detoxification. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 6741–6769, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Analyzing Bias in False Refusal Behavior of Large Language Models for Hate Speech Detoxification (Yuan et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.319.pdf