Failure Modes for Large Language Models in Islamic Legal Reasoning

Millions of Muslims consult large language models (LLMs) for Islamic legal guidance, yet the specific failure modes of LLMs in this domain remain uncharacteristic. The Islamic jurisprudence fiqh is characterized by authenticated transmission chains isnad, codified schools of law, formal certainty grades qat./zann, and institutionalized scholarly authority. One can map open problems at the intersection of AI and Islamic law into open problems in LLM reliability, calibration, and alignment. We present a six-category failure mode taxonomy grounding each failure at the intersection of a classical jurisprudential concept and a specific ML failure class, derive evaluation criteria for each mode, and propose a research agenda connecting us. ul al-fiqh epistemology to ML methodology. We conclude that fiqh is a productive and underexplored test-bed for formal legal AI.