This paper uses Ottoman archival sources and published court documents to chart a vitally important encounter between the Ottoman Empire and the European-dominated international legal system that has never received sustained study by historians. The Ottoman and Russian Empires fought eleven wars between the seventeenth and twentieth centuries, culminating in their mutual demise during the First World War. But in 1912, the two Eurasian empires took their differences to a new venue: not a military campaign in the Balkans, but a legal arbitration. The Ottomans had agreed to pay indemnities after losing the 1877-78 Russo-Turkish war, but they had not fully paid. Now, Russia wanted its money. So representatives of the tsar and sultan traveled to the Hague to argue, in French, before the Permanent Court of Arbitration. Idealistic Atlantic activists had conceived of this court as a utopian alternative to war, and the agrarian empires of Eurasia now used it. The resulting Russian Indemnities case—unlike most Ottoman encounters with international law—is better known today among lawyers than historians. The court ordered the Ottoman state to pay both the indemnities and interest on them, rejecting the Porte’s expansive claim that no state could be bound to pay moratory (penalty) interest without its express consent. This seemingly picayune legal point paved the way for the modern regime of sovereign debt and global governance. By combining the published record with contemporary European commentaries and Ottoman archival documents, I will argue that Ottoman, Russian, and western European arguments reflected not just states’ own interests, but also their deeper commitments to overarching theories of international law. The Ottoman state took a sharply positivist position. The laws that bound it, the Porte maintained, came only from formal agreements. There was no law without consent. This Ottoman view was now defeated by a more expansive European claim: that all states were bound by a thick web of custom, the contents of which were determined by Europeans. The case thus illuminates a critical historical moment, when the promise of arbitration as a utopian, pacifist project collided with the racism inherent in international law, the ominous approach of World War I, and the Ottoman state’s increasingly desperate struggle to save itself by any means necessary.