usuline

Usuline, also spelled Usuli, is an adjective referring to Usulism, a school of thought within Twelver Shia Islam that emphasizes the use of ijtihad and reason in deriving religious law. The term derives from usul al-fiqh, the "roots" or principles of jurisprudence, and its adherents are often described as Usulis.

Historically, Usuli and Akhbari were two competing approaches to Shia jurisprudence that emerged in the Safavid period and continued into the modern era. Akhbaris prioritized strict reliance on transmitted hadith and a limited set of sources, while Usulis argued that qualified jurists could interpret the scriptures through rational methods. By the 18th and 19th centuries, Usuli methods became dominant in centers such as Najaf and later Qom, shaping modern Twelver jurisprudence and the practice of religious authority.

Doctrinally, Usulism holds that a qualified jurist (faqih) may perform ijtihad and issue legal rulings. Over time a hierarchical structure developed in which mujtahids and, in many communities, a leading marja' al-taqlid (source of emulation) guide followers. The Usuli framework relies on multiple sources of law, including the Qur'an, Hadith as interpreted through the Usul al-Fiqh, and the roles of consensus (ijma) and reason (aql). Compared with earlier approaches, reason and methodological principles play a central role in deriving legal rulings within Usulism.

Today, Usulism underpins contemporary Twelver Shia jurisprudence and the practice of clerical authority in many communities, notably in Iran and Iraq, where maraji' issue fatawa and guide religious conduct and public life. The term distinguishes a jurisprudential method from other Shia approaches that emphasize different sources or methods of interpretation.