This conceptual paper reconstructs an implicit ethical claim of post-normal science, namely that knowledge produced in extended peer communities (EPCs) is both epistemically better and fairer. Post-normal science introduced EPCs to operationalise better quality knowledge for decision-making in conditions when facts are uncertain, values in dispute, stakes high and decisions urgent. In such contexts, traditional forms of quality assurance in science are bound to fail and even risk becoming the source of harm to people, their social and natural environment. Consequently, the community of peers assessing the quality of knowledge needs to be broadened to include a plurality of perspectives and epistemic communities. To date, post-normal scholarship has focused primarily on the epistemological side of EPCs. Building on this, this paper addresses the ethical side of EPCs. In doing so, it aims to make explicit a claim that has always been at the heart of post-normal scholarship, namely that the knowledge produced in EPCs is also more just. In doing so, the paper builds on the literature on epistemic (in)justice and in particular on work done by Kristie Dotson.