The deliberative systems approach perceives public deliberation as a broad system that encompasses diverse communicative practices and emphasises the connectivity and interdependence of its components, division of deliberative labour and functions, and how crucial components interconnect to enhance the deliberative quality of the system. Drawing on deliberative systems theory and the epistemic approach to democracy, this study investigated the controversies surrounding a development project in the traditional Thao territories of the Sun Moon Lake region, with the objective of exploring epistemic oppression and how citizen action performs functions of deliberative systems and deliberative power. The study shows that the Thao tribe’s narratives and testimonies of their life have not been valued, multiple forms of epistemic oppression, and the decoupling problems that exist between empowered spaces and other components in deliberative systems. To combat epistemic oppression and coercive power and safeguard traditional territories and cultural subjectivity and continuity, the Thao tribespeople and civic society