In 1830, following the conquest of Algiers, French statesmen began to systematically deny Ottoman sovereignty claims over Tunis, Algeria’s eastern neighbor. Tunis was an autonomous province of the Ottoman Empire since 1575, placed under the hereditary rule of the Husaynid Beys since the early eighteenth century. However, in an attempt to undermine Ottoman influence in North Africa, France began to treat the Beys as independent ruler and Tunis as a sovereign state. In support of their government’s position, French diplomats devised a number of arguments designed to “prove" that Tunis was independent from Istanbul. One French argument conceded that the Ottoman sultan held a form of authority over Tunis, but argued that this authority was merely religious – and therefore symbolic. Implicit in this view is a conception of sovereignty predicated on a strict separation between temporal (real) and spiritual (symbolic) authority. This separation, the Sublime Porte argued, was foreign to the Ottoman understanding of sovereignty. According to the latter, the sultan’s authority as a caliph was indissociable from his sovereign authority as a ruler. This paper examines the French argument about the nature of caliphal authority and the Ottoman responses to it. In doing so, I attempt to unearth an Ottoman conception of the relationship between secular and caliphal power, and shed light on how diverse ideas about imperial sovereignty circulated across legal traditions in the nineteenth-century Maghrib.