Megaregional trade negotiations have become the subject of heated debate, above all in the context of the Transatlantic Trade and Investment Partnership and the Trans-Pacific Partnership. In this article, I argue that the justice of the global order suffers from its institutional fragmentation into regime complexes. From a republican perspective, which aspires to non-domination as a guiding principles and idea of global justice, regime complexes raise specific and important challenges in that they open the door to specific forms of domination. I thereby challenge a more optimistic outlook in regime complexes, which paints a positive normative picture of regime complexes, arguing that they enable the enhancement of democracy beyond the state and, consequently, have the potential to reduce the democratic deficit in global governance. By drawing attention to how regime complexes reinforce domination-related injustice, this article contributes an original perspective on megaregionals and to exploring the implications of global justice as non-domination.