The current PhD project attempts to analyse the impact of compliance committees under multilateral environmental treaties (METs) on national legal systems. This project will measure the reception by the variety of legal orders of the output of compliance committees under twenty METs. In order to conduct the impact assessment, we adopt a methodology that is at the crossroads of political science and legal scholarship. The preliminary thesis dissertation discusses in details research question, advances on the functional and methodological traits of impact assessment of compliance committees and critically analyses the environmental law literature. It provides also the detailed work plan for upcoming two years. Since the current project has empirical orientation, all the methodological claims are supported by the case samples from all compliance committees."