In this study of a postcolonial school, we expand understandings of epistemic justice from the perspective of language, addressing issues of know-ledge, understanding, and participation in communicative practices. We suggest that monoglossic language-in-education policies constitute a form of epistemic injustice by diminishing learners' ability to make epistemic contributions, a capacity central to human value. We further suggest that translanguaging in formal school settings generally promotes "epistemic access" rather than "epistemic justice," leaving value hierarchies and relations of knowing unchanged. Conversely, this study presents linguistic ethnographic data from a three-year project where learners could choose their language of learning to Grade 6 and use all languages in subject classrooms. We analyse how a Grade 6 learner used laminated, multilingual stances to construct others as knowers, negotiate epistemic authority, and promote solidarity. We argue that she thereby constructed new decolonial relations of knowing and being. Moreover, the shift from monolingual to multilingual episteme, which substantially improved performance overall, enabled new social, epistemic, and moral orders to emerge from below, laying the basis for greater epistemic justice.