Based on the French notion of terroir or ‘the taste of place,’ a certified geographical indication (GI) identifies an agro-food product as originating in a particular territory and suggests that its quality, reputation, or other characteristics are essentially or exclusively attributable to its geographical origin. Previous scholarship exploring the social construction of terroir has focused on how disparities in political, economic, and cultural power shape GI regulations, certification procedures, and territorial boundaries. While these works have considered knowledge as a resource (...) deployed through relations of authority, studies of GI implementation have not adequately considered an important aspect of power in contemporary politics: the epistemic authority to assert the legitimacy of knowledge and its relevance to policymaking. In contrast, in this article, I take the accomplishment of epistemic authority – to determine the ‘essential’ and ‘exclusive’ physical and/or cultural attributes of place that shape product character – as key to the social construction of terroir and the institutionalization of GI regulations. This process is explored through a case study of Ecuador’s 2013-2019 implementation of a GI for Galápagos Islands coffee. I draw on analysis of relevant policy and regulatory documents and semi-structured interviews with 21 key stakeholders to argue that analytical attention to the legitimacy and relevance of terroir knowledge explains how coffee producers were able to deploy authoritative knowledge to disrupt and reinforce relations of authority and challenge the terms and mechanisms of GI qualification. (shrink)