Due to the jurisdictionalism inherited from Portugal, and in view of the strength of the typically liberal idea of sovereignty defense, the Empire of Brazil initially adopted as course of action to prohibit foreign priests from holding ecclesiastical benefices in its territory. The article focuses on the legal transformations that took place in the second half of the nineteenth century, and which led to a relativization of this prohibition, especially in view of the massive migration of European priests to the Americas in the period. We analyze concrete cases presented by bishops and clergymen to the Council of State, the emperor’s advisory body, as well as to the Congregation of the Council, an administrative organ of the Holy See, and show how a path was paved for the multilevel regulation of the migratory flows of the secular clergy towards Brazil. Since the Council of Trent was a key normative set to organise the mobility of clergymen around the globe, we examine how institutions and actors that ordinarily made use of it forged new interpretations and new norms in order to discipline migration as an unprecedented phenomenon. Following up on the Tridentine, transformations will allow us to see how precarious the situation of foreign priests was in terms of belonging to a new country and a new diocese. It will also reveal that what kept the clergymen minimally anchored in the sea of legal uncertainties at the end of the 19th century was the notion of duty.