Commercial lawyers working across borders know that globalization has changed commercial law. To think of commercial law as only the law of states is to have an inadequate understanding of the norms governing commercial transactions. Some have argued for a transnational conception of commercial law, but their grounds of justification have been unpersuasive, often grounded on claims about the common content among national legal systems. Legal positivism is a rich literature on the concept of a legal system and the validity conditions for rules in legal systems, but it has not been used to understand legal order outside or beyond the state. This article aims to use legal positivism to conceptualize a transnational commercial law order. Prevailing positivist accounts at least implicitly condition legal order on state sovereignty. The article offers a cosmopolitan conception of legal positivism, in which the state is no longer an enabling condition for law. The cosmopolitan conception provides the means by which to adequately describe a transnational commercial law order. There are limits to the conceptual analysis this article provides, one of which is that it does not purport to evaluate the justice or morality of transnational legal order. But the cosmopolitan conception of legal positivism elucidated in this article stands on its own as a way of understanding a number of transnational legal orders other than commercial law. The attractiveness of the account is that it describes law as a human social practice even when it is not solely the product of the state, so that we do not have to rely on natural law theories to understand legal rules that states do not maintain.