This thesis is about the life and thought of the scholar Muhammad b. ʻAli al-Shawkānī (d. 1250/1834) and his continuing influence on Yemeni law and society. It is argued here that in order to better understand Shawkānī one must look at the history of the Qāsimī imāmate he served. In the 17th century the imāms lived up to the ideal posited by Hādawī-Zaydī law. They were learned men and able military commanders in their own right and authority was largely based on charisma. In the 18th and 19th century in contrast, the imāms lacked the qualities evident in their predecessors and behaved more like kings. Rule became dynastic and took on patrimonial forms. A further development during the 18th century was the increasing influence of Sunnī Traditionist views among Zaydī-born scholars in northern Yemeni highlands. With the imāms now offering their support to Sunna-oriented scholars, the Hādawīs increasingly become marginalised. These changes were also accompanied by considerable territorial losses by the imāmate and a decline in its revenues generated from the coffee trade. The alliance between the imāms and the Sunna-oriented scholars became most evident when Shawkānī was appointed chief judge (qāḍī al-quḍāt) of the imāmate. It will be argued that his views on law and reform posited an alternative vision of order and righteousness to that espoused by Hādawīs. His teachings implied that he, in his capacity as mujtahid muṭlaq, was to be the ultimate legal authority to which others must defer. Moreover, his views on the institution of the imāmate refuted the conditions set by Hādawī law and legitimized the rule of the imāms he served. The imām, according to him, need not be a mujtahid and rebellion against him (even if he were unjust) was absolutely forbidden. With the support of the imāms, Shawkānī was able to implement his views. His influence was manifested in his ability to appoint his students to administrative posts throughout the realm. All of this engendered a reaction from the more traditional Zaydī scholars and several clashes, both scholarly and in the form of popular riots, ensued. After his death Shawkānī's views were carried on by his students who continued to teach his works and the Sunnī ḥadīth collections until modern times. The 20th century Ḥāmīd al-Dīn imāms were interested in publishing Shawkānī's works in order to show the wider Muslim world the convergence between Zaydism and Sunnism. After the 1962 revolution republican intellectuals further focused great attention on Shawkānī in order to undermine the legitimacy of the imīmic regime and for nationalist ends. By making appeal to his views they have tried to mould Yemeni religious identity away from the Zaydī legacy of the past.