This paper addresses the question of controversy in a recent and harsh environmental and healthcare dispute regarding GMO and food safety, and the consequences of this controversy on public confidence in scientists, media and institutions. More specifically, with a case study on the “Séralini Affair” of 2012 – an international controversy over genetically modified foods and science mediatisation – we analyzed how key players engaged themselves in a conflict. Using a qualitative methodology, we observed media and communication strategies during the polemic and conducted more than fifteen interviews. We therefore investigated the profound cultural questions raised by the antagonism between scientists, media, institutions, civil society and lobbies. The goals of this research are to propose new ethics for dispute and conflict resolution under the umbrella of the Foucaudian concept parrhesia – frankness – and to understand how effective can mediation be in environmental and healthcare dispute contexts.