The Aarhus Convention, as well as envisages a minimum of internal enforcement of the public participation in environmental matters, has enabled the establis- hment of an innovative compliance mechanism in which the public can bring communications on the noncompliance of the Parties. In this paper, afterwards a succinct exposition of the foundation of the public participation in environmental matters and its form of address in Aarhus Convention, it is explained the do- mestic enforcement therein prescribed and the aforementioned accomplishment mechanism. As soon as this basis were set up, the noncompliance cases involving public participation settled by the compliance mechanism are analyzed, from which is determined its efficiency in the enforcement of the public participation in environmental matters at the international level.