From the late fifteenth century onward, the diplomatic instruments that regulated peaceful relations between the Ottomans and the Venetians, the ahdnames, contained clauses prohibiting piracy and the enslavement of each other’s subjects. By the seventeenth century, however, the sultan’s nominal subjects in North Africa were not only regularly violating these provisions—with Tunisian and Algerian corsairs routinely attacking Venetian ships and raiding Venetian shores—they were also challenging the articles’ legitimacy. Indeed, the ahdnames, which were framed as unilateral sultanic decrees, had little grounding in Islamic law. A series of raids by Tunisian corsairs on Venetian targets in the 1620s brought the issue to a head, with Tunisian representatives in Istanbul arguing after the fact that the principles of retaliation, custom, and Islamic law gave them the right to stage attacks against Venice irrespective of whatever the ahdname promised. Following this, Ottoman officials turned to the ?eyhülislam Zekeriyyazade Yahya Efendi, the Empire’s chief jurisconsult, to address the matter of how and why the ahdname was binding upon the Tunisians according to Islamic law. Tracing the controversy across Ottoman and Venetian sources, this paper examines the ?eyhülislam’s response to the issue, laid out first in letters, then in a series of fatwas, exploring how he used the gravitas of his office to reinforce the religious legitimacy of the otherwise secular ahdnames. The end result was a stark reaffirmation of the sultan’s sole right to declare and direct holy war, making any unauthorized raid an act of criminal rebellion.