Even at the beginning of the third millennium, questions of participation, democracy and the separation of powers in the Catholic Church are of great contemporary relevance. How can participation be realized within the hierarchical system of the Catholic Church? What understanding of synodality is needed for this? To what extent can or must the church open itself up to socially recognized legal principles such as democracy and the separation of powers? Canon law plays a central role in this regard, as it must provide the legal instruments to enable the implementation of synodal structures, participatory processes, and elements of the separation of powers. Analogous to the concept of "Rechtsstaatlichkeit" (for which there is no exact equivalent in English; it is usually translated as "rule of law" or "state of law"), the Austrian theologian Valentin Zsifkovics coined the term of "Rechtskirchlichkeit" (i.e. roughly "rule of law in the Church"). The paper aims to examine to what extent this concept can be a helpful impulse for the further development of the church's legal system in the third millennium. How must church law be structured so that it guarantees a "legal church" order, i.e. does not fall short of contemporary legal standards while at the same time retaining the proprium of the church's self-image and mission? How can elements of democratic decision- making culture be implemented in the church without abandoning the specifically Catholic understanding of the ministry? Is "Rechtskirchlichkeit", analogous to "Rechtsstaatlichkeit" in the public context, conceivable? How could this encompass the sacramental ministry on the one hand and contemporary forms of participation on the other?