Judicial cooperation in environmental matters is a key aspect of the move towards environmental democracy undertaken by the European Union. This Article presents the preliminary findings about the kind of behaviour that national courts can show with their judgments once they received a preliminary ruling from the Court of Justice of the European Union, so-called follow-up judgments. It first shows the results of the latest two empirical studies, namely that Italian and Belgian courts tend to cooperate fully with the Court of Justice in environmental matters. Besides, only one new category of judicial cooperation is highlighted, that of suspended cooperation. The unfolding of the categories of judicial cooperation seems to have reached the saturation point. Accordingly, this Article presents the first quantitative and qualitative findings that emerge when looking at judicial cooperation in follow-up judgments from five jurisdiction: next to Belgium and Italy, also the United Kingdom (UK), Sweden, and the Netherlands. This comparison suggests that country-by-country, theme-by-theme and case-by-case circumstances influence national courts behaviour, potentially affecting the level of environmental democracy enjoyed in certain Member States. Accordingly, this Article introduces an empirical research agenda to investigate factors and reasons explaining the findings, therefore contributing to the improvement of judicial cooperation in environmental matters.