A large body of research examines states' efforts to increase international trade through public law, that is, by forming preferential trade agreements (PTAs) that lower governmental barriers to trade. Scholars, however, have overlooked another mechanism through which states seek to facilitate trade: international harmonization of private law. Underlying legal harmonization is the assumption that cross-national variation of commercial law impedes trade; by contrast, similarity of laws across countries encourages trade by reducing uncertainty and transaction costs.