Starting from the origins of the Liberal tradition of political thought, this article tracks back the roots of the link between trade and democracy. They are to be found in the idea of "economic commerce" from the writings of Montesquieu and Olson's political economy work on the nexus between regime representativeness and fiscal policy choices to the most recent empirical literature on the "democratic difference". The assumption that, for causes of both fiscal optimization and policy constraints exerted by a protectionist legislative on the executive, democracies are more prone towards free trade than non democracies. This study proves that domestic political regimes have an impact on the level of bilateral trade among great powers, while also endowing with robust empirical evidence the proposition according to which pairs of democratic states tend to trade more with each other than mixed pairs (e.g. pairs composed by a democracy and an autocracy) do. Furthermore, this research stands as the first empirical test of the relevance of the difference for trade made by democracy after the end of the Cold War and the democratization of Russia.