Promoting trade through private law: Explaining international legal harmonization

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. I argue that the harmonization of private law acts as a substitute for the public-law channel of stimulating trade: countries with limited PTA partnerships make up for this deficiency by joining initiatives for private-law harmonization. This argument is tested by analyzing the UN Convention on Contracts for the International Sale of Goods-one of the primary instruments of legal harmonization. Indeed, countries that are party to shallow PTAs or have few PTA partners are more likely to ratify this private-law convention. Overall, this article urges scholars of trade and international law to broaden their research agenda to include private law.