Ideas and practices often perceived as modern carry a complex premodern history that cannot be excised from their present. This is certainly the case of trade embargoes as economic means for the attainment of political goals. For a variety of reasons, however, tracing change over long periods of time remains an exercise in chronological and spatial jurisdiction. Further complicating our understanding of the convoluted relationship between past and present has been the increasingly pronounced tendency to write in the vein either of a “history of ideology” or, conversely, of a “history of action.” In fact, “theory” and “practice” existed in a dialectical relationship, a cyclical tug of war that produced not so much winners and losers as complex realities that require a thick reading of legal, political, cultural, and social change. This chapter, by contrast, seeks to explain the transfiguration of the legal tradition from the perspective of international law history by focusing on two interrelated transitions.

The question of rights for non-Christians emerged out of a theocratic papalist conception of world order during the medieval crusades typified by the canon lawyer Sinibaldo Fieschi (later Pope Innocent IV). It then informed the dominant and ambivalent legal view of Christian-infidel relations in Latin Christendom represented in very different ways by both Innocent IV and his creative commentator, Polish jurist Paulus Vladimiri. This chapter considers the political translation of Innocent’s canon legal opinion on Christian-infidel relations to support the Iberian cause of missionary war in spreading the faith through Crown and Empire across the Atlantic. Theocratic world order, as articulated by Spanish royal jurists and conquistadors like Juan López de Palacios Rubios and Hernán Cortés, chiefly rested its justification for European expansion on the right of punishing infidels for their violation of natural law, the sin of idolatry above all. Infidels had dominium, in principle, but Europeans could claim superior jurisdiction over them when they presented obstacles to the spreading of religion and civilization.