While the founder of international law was long considered to be Hugo Grotius, attempts were made in the late 1920s and early 1930s to dethrone him in favour of the Spanish theologian Francisco de Vitoria. This took place as the professionalization of the field of international law was reaching its golden age both in Europe and the Americas. Leading this case were the prominent US jurist James Brown Scott, one of the founders of the American Society of International Law, and the Spanish jurist Camilo Barcia Trelles. But why did they decide to revive Vitoria then, and why would they couch him specifically as the founder of international law? This article focuses on the intellectual history of the canonization of Vitoria in the context of the formation and consolidation of a continental Pan-American ideal and network of American international law in the Americas. Particular attention is paid to the American Institute of International Law, presided by Scott, and the formation of a Spanish Americanist cultural tradition in Spain. The latter deeply influenced Barcia, who developed a profound interest in Latin American questions, notably around the Monroe Doctrine. The article argues that these geopolitical Pan-American and Spanish-Americanist anxieties of re-unifying the Americas and Spain/America strongly influenced the depiction of Vitoria as a new founding father of international law and allowed Scott and Barcia to elevate themselves as Vitoria’s heirs.