As a basic point of reference in international law the Aarhus Convention has a considerable impact on the framework of public participation in environmental matters. The fact that the Convention forms part of national legal orders of EU Member States both as part of international and EU law, the proper enforcement of its provisions makes it inevitable to draw up certain principles of interpretation. The current paper aims to analyze how the Aarhus Convention appears at the level of legal argumentation in the case-law of the CJEU and selected national constitutional courts or high courts of EU Member States, namely, Germany, France and Hungary. Those decisions are examined that refer directly and explicitly to the Aarhus Convention. The case-law analysis is completed by the reference to the relevant secondary literature. The findings can provide a synthesis about the role of the Aarhus Convention, thematic milestones can be drawn up concerning the interpretation of the obligations stemming from the Convention and they can give useful insights into the relationship of national laws, EU law and international law. Meanwhile, they contribute to the analysis of the role of civil participation in the protection of the environment. This way, the conclusions can support the emergence of a (more) general approach in EU Member States as far as public participation in environmental matters is concerned.