At a critical moment during the Napoleonic era, the stockbrokers of Paris were summoned before the Council of State to defend the marché à terme, or futures contract in public debt. Surprisingly, despite official disdain and ample legal opportunity for prohibition, the brokers’ argument was successful, and the marché à terme escaped repression. The defense of the marché à terme turned on the nature of property. To critics, it divided property from possession, severing property from any concrete anchors. Advocates, by contrast, pointed to the inherent abstraction of property encoded in legal norms. These debates helped shape a concept of property in which economic utility, legal validity, and moral grounding converged. As a central pillar of the new regime, this concept of property also constrained political authority. The successful defense of the marché à terme shows that property was a right that not even authoritarian regimes could restrict arbitrarily.