The period between the Peace of Augsburg (1555) and the Thirty Years War (1618-1648) was crucial for the redefinition of the powers within the Holy Roman Empire. The problem was not limited to sovereign rights but directly involved the redefinition of the prerogatives of the Church according to the Reformation ideals. In this context, a new discipline called ius publicum emerged, with the aim to stabilize issues and establish borders between the various organs of the nascent modern state. Henning Arnisaeus’s (1576-1636), De iure maiestatis (1610) and Dietrich Reinking’s (1590-1664) Tractatus de regimine seculari et ecclesiastico (1619) represented two fundamental contributions to this debate. They were important sources for the theologian Hans Wandal (1624-1675), pioneer of the Danish absolutism, who also published a treatise dedicated to the subject: Jus regium libri VI (1663-1672). Focusing on these three key authors, this paper will discuss the relationship between political and ecclesiastical authority as this was imagined in post-reformation thought and its transmission from the Holy Roman Empire to the Danish Kingdom. It will pay special attention to the notion of “potestas” and its limits in the German and Danish context.