The article analyses the manner in which the Independent Expert Panel’s definition of ecoide, according to international law experts, has been critiqued as posessing two biases. First, anthropocentrism understood as the mechanism of overestimating human benefit and underestimating environmental cost. Second, short-termism or temporal discounting of environmental risks, understood as the preference for immediate benefits at the expense of long-term gains. The disputed part of the definition is the proportionality test in the form of a cost-benefit analysis, which we argue to be subject to the affect heuristic. Some experts have suggested lowering the required mental state (mens rea) threshold in the definition from intent and knowledge to recklessness and negligence. In three experiments (N = 919), we find that the two biases indeed affect the ascriptions of mental states, proportionality and responsibility based on the current phrasing of the definition. Thus, in line with previous research in environmental psychology, we find that moral emotions impact environmental judgement. We also find that mentioning future generations, as well as their harm in the form of lack of access to drinkable water (resource dilemma), constitutes an effective countermeasure to the bias. Finally, we find that lowering the mens rea threshold alleviates probative difficulties and helps reduce bias. We propose replacing the cost-benefit analysis in the proportionality test with an impact assessment tool.