Fiqh, derived from the root meaning “to understand,” is the term used for jurisprudence. The closest Qur’anic usage (9:122) refers to those who “become learned in religion [yatafaqqahu].” Jurisprudence is often said to be the most important of the Islamic sciences and it is part of a cluster of related concepts that structure Muslim legal norms and practices. Jurisprudence, which solidified into a discipline during the fi rst Muslim centuries, is not precisely equivalent to law in the modern sense. Rather, like Jewish halakhah it governs both social and ritual obligations, and concerns itself with questions of moral and ethical correctness, not only legally binding rights and duties subject to adjudication. Fiqh is the human attempt to interpret and implement the shari‘ah, God’s revealed law. Unlike shari‘ah, which is understood to be universal, complete, and perfect, fiqh is a human discipline that involves disagreement and development over time. Historically, these differences have resulted in the creation of legal schools (sing. madhhab). Sunni and Shi‘i models of jurisprudence are similar in many respects. The most striking difference, apart from the specifi c hadith compilations deemed authoritative, are in their approaches to the issue of authority and precedent. Although the view that the “gates of ijtihad”—independent legal thought—were closed by medieval Sunni jurists has been effectively debunked by recent scholarship, following precedent (taqlid) continued to be important. Among Shi‘is, however, the rule is that one must always follow a living mujtahid, known as a marja’- i taqlid or model for emulation. In their work, jurists must mediate between the provisions of source texts and the customs and requirements of diverse social circum stances. In developing substantive doctrines—which were argued over and debated across and even within madhhab lines—the jurists relied on the theoretical framework known as usul al-fi qh, “the roots of jurisprudence.” In its developed form, Sunni legal methodology relies on Qur’an and sunnah, the two textual roots of the law; qiyas or analogy; and consensus, ijma‘. Some schools rely on supplementary legal principles, such as ‘urf (custom), or maslahah (public interest). Modern attempts at legal reform often rely on these subsidiary principles to work around specifi c doctrines rather than radically reinterpret their bases.