Arabic Safety Alignment as Selective Refusal: An Empirical Study of SFT, DPO, and Guard Calibration

Mohammad Zbeeb, Ammar Mohanna


Abstract
Arabic large language models must refuse harmful prompts without over-refusing benign or sensitive prompts, yet a single refusal rate hides this trade-off. We evaluate it using benign refusal B and harmful-prompt refusal H, where H measures refusal rather than harmful compliance. Across five Arabic-capable models and 130 runs on the full human-written AraSafe set, refusal-only supervised fine-tuning (SFT) collapses toward blanket refusal, whereas selected mixed-SFT configurations reach H≈90–93% at B=14–23%; four selected configurations exceed H=90% in all three runs, while Fanar does so in two of three. Direct Preference Optimization (DPO) and inference guards change B and H differently across models rather than acting as uniform upgrades. In a blinded 300-response audit, annotator binary-refusal agreement is 89.0% (𝜅=0.78); Qwen3Guard and Aya Expanse 32B reach 88.7% and 91.0% accuracy, respectively, with no conclusive paired difference. Selected SFT raises H on Arabizi for all five models, but none reaches 90%, showing only partial transfer from Modern Standard Arabic; overall, the results support model-specific operating-point selection: set a deployment target and retain only interventions that improve it.
Anthology ID:
2026.arabicnlp-main.17
Volume:
Proceedings of The Fourth Arabic Natural Language Processing Conference
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Muhammad Abdul-Mageed, Tamer Elsayed, Houda Bouamor, Samhaa El-Beltagy, Hend Al-Khalifa, Ahmed Abdelali, AbdelRahim Elmadany, Abdellah El Mekki, Kareem Darwish, Sakhar Alkhereyf, Hamzah Luqman, Salam Khalifa, Samar Magdy, Zaid Alyafeai, Injy Hamed, Wajdi Zaghouani, Imed Zitouni
Venue:
ArabicNLP
SIG:
SIGARAB
Publisher:
Association for Computational Linguistics
Note:
Pages:
228–246
Language:
URL:
https://aclanthology.org/2026.arabicnlp-main.17/
DOI:
Bibkey:
Cite (ACL):
Mohammad Zbeeb and Ammar Mohanna. 2026. Arabic Safety Alignment as Selective Refusal: An Empirical Study of SFT, DPO, and Guard Calibration. In Proceedings of The Fourth Arabic Natural Language Processing Conference, pages 228–246, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Arabic Safety Alignment as Selective Refusal: An Empirical Study of SFT, DPO, and Guard Calibration (Zbeeb & Mohanna, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-main.17.pdf