Based on traditional legal research analysing judgments, third-party interventions, NGOs’ grey literature and the study of semi-structured interviews conducted over the last six months, this paper offers a critical analysis of NGOs’ and NHRIs’ interventions in environmental and climate cases brought before the European Court of Human Rights (ECtHR), focussing on the strategies of the actors involved and the impact of their interventions. We show how these interventions are the work of interconnected minority actors, most of whom act as repeat players. Due to the privileged relations these associations and institutions have with the ECtHR, these actions are beneficial to both actors. Nevertheless, these actions remain risky, entailing significant costs for the Non-Governmental Organisations (NGOs) and National Human Rights Institutions (NHRIs) involved, with an overall limited impact on European jurisprudence and not without risks to their independence. We will examine how climate litigation may or may not renew such interventions. This contribution thus offers a new perspective on these actors, which goes beyond the usual presentation in the academic literature, which tends either to sacralise or, conversely, to downplay these actions, neglecting the question of the control of these interventions by the Court. It is precisely this gap that this paper attempts to document by focussing on environmental and climate cases.