Many studies have deduced subterranean dialogues between Hannah Arendt and Carl Schmitt from indirect evidence. This article uses new evidence from marginalia in Arendt's copy of Nomos of the Earth and finds that she formed, but never published, an incisive critique of Schmitt's geopolitics. Through an analysis of Arendt's comments on the topics of soil, conquest, and contract, I show that Arendt deemed Schmitt's theory to be imperialist and in contradiction with itself. Her reading of Schmitt prompts important new questions regarding the scholarly use of Schmitt's conception of nomos as a tool of critique against American empire in the post-9/11 era. The marginalia also suggests, against past scholarship, that Arendt thought justice should play a central role in politics. I propose that we look to Arendt's own conception of nomos, which she developed later, in order to form an alternative geopolitics. Because of her focus on intersubjective world-building, Arendt's nomos embraces contract and promise-making, and thus provides the foundation for a theory of geopolitics and law that is as necessarily democratic as Schmitt's is violent.