Recent developments in international environmental law are increasingly characterized by the concern with ensuring the effectiveness of existing international environmental obligations, as well as by a growing awareness of the need to adopt a comprehensive and integrated approach in the management of natural resources. Non-compliance mechanisms are generally assumed to be better than courts for achieving these aims. This chapter assesses this assumption through the analysis of the Gabčíkovo-Nagymaros and Bystroe Canal cases. Despite a judgment of the International Court of Justice (ICJ) in Gabčíkovo-Nagymaros and the triggering of non-compliance procedures in Bystroe Canal, both cases are still pending or have remained substantially unsettled. In particular, this chapter compares the approaches adopted by the ICJ and the competent monitoring bodies, evaluating their respective contributions to: balancing the parties’ conflicting interests; stimulating meaningful and fruitful co-operation of the parties towards an agreed solution; integrating the interests of the parties concerned with the interests of other States, individuals or group of individuals and the global environment.

Non-Compliance Procedures are designed to facilitate the compliance of States parties with obligations deriving from Multilateral Environmental Agreements but may trigger harsher means to elicit compliance such as suspension of a party’s rights. The chapter will analyse the classical NCPs such as those in the Montreal Protocol on Substances That Deplete the Ozone Layer, the Convention on International Trade in Endangered Species of Wild Fauna and Flora, the Convention on Access to Information, Public Participation in Decision-making and Access to Justice in Environmental Matters and the Kyoto Protocol. It will then analyse the new type of NCPs, established in the Paris Agreement and the Rotterdam Convention on the Prior Informed Consent Procedure for Certain Hazardous Chemicals and Pesticides in International Trade and the Convention on the Protection and Use of Transboundary Watercourses and International Lakes. This chapter will analyse whether compliance is better ensured by more facilitative rather than coercive methods, together with NCPs’ legitimacy, including with reference to the powers of Conferences or Meetings of the Parties which mostly decide on non-compliance.