Doctrinal disconnects complicate adjudication of international water rights controversies. However, legal history and comparative law sources can fill gaps and build analogies to bridge differences in substantive law. Between Mexico and the United States in particular, the civil-common-law divide at times appears vast, but has been occasionally narrowed by reference to shared Roman principles of usufruct or by incorporation of Mexican law into the U.S. system. Such meeting places for doctrine suggest that, even in domestic courts, nations need not attempt to resolve international problems through domestic law alone.