Treats the strands of Shi'ite legal theory as a family of legal traditions, providing illustrative examples with editions of previously unpublished works Examines for the first time in English an intergrated analysis of Shiite traditions and legal theories, including the validity of personal juristic reasoning (ijtih?d), linguistic interpretations, the role of certainty in the deduction of law and the legal authority of the im?ms Covers Shi?i u??l, which has received little attention in scholarly discussions of Islamic legal theory Focuses not only on the less-neglected Twelver u??l but also on Isma?ili and Zaydi u??l traditions Presents texts from a range of regions (Yemen, Iraq and Safavid Persia) and written across a broad time period (from the 5th/11th century to the 13th/18th century) Incorporation of Zaydi, Isma?ili and Twelver legal traditions in a single analytical framework Alongside the individual rules of God's law ( shar??a ), there has been a vibrant history of more philosophical or theoretical discussions in Islamic thought. Where does God's law come from? How are God's rules to be discovered for situations not covered in the revealed sources? Who, within the Muslim community, can make a valid pronouncement on the content of the shar??a ? The answers to these questions have been debated and discussed by Muslim scholars in the genre of literature called u??l al-fiqh , glossed in English language secondary literature as "Islamic legal theory". This volume contains editions and commentaries of hitherto un-edited manuscripts from the various strands of the Shi?ite tradition of Islamic thought (Zaydi, Isma?ili and Twelver). A careful side-by-side reading of these texts and commentaries will help identify themes peculiar to the Shi?ite "family" of legal theories. The distinctive Shi?ite contribution to the history of u??l al-fiqh has not received the attention it deserves in contemporary scholarship; this volume forms part of wider attempt to bring the richness and diversity of Shi?ite u??l to the wider field.