In the nineteenth century, Tunis was an autonomous province of the Ottoman Empire, placed under the hereditary rule of a local governor known as the Bey. However, in 1881, France established its colonial presence in Tunis. Despite the Bey’s request for assistance, the Ottomans could do little to prevent French occupation on the ground. Legally, however, Istanbul continued to claim Tunis as its province. This paper examines the Sublime Porte’s strategy of legal resistance in its efforts to sustain its sovereignty claims over occupied Tunis. A critical dimension of the French-Ottoman dispute over sovereignty in Tunis was the question of the legal belonging of Tunisians established in Ottoman-ruled territory. Were they Ottoman nationals or French colonial subjects? After 1881, the jurisdictional status of Tunisians became a stake of the larger, more fundamental question of sovereignty. The paper focuses on the legal ways in which the Sublime Porte argued in favour of the Ottoman nationality of Tunisians.