The focus of this chapter is on the enforcement of public rights to information and participation in transboundary environmental impact assessment (TEIA),1 with specific reference to the transposition of the United Nations Economic Commission for Europe (UNECE) Espoo2 and Aarhus3 Conventions in EU law.4 The non-discrimination principle, which is recognized by the Aarhus Convention5 and Treaty on European Union,6 permits individuals and NGOs of one state to exercise these rights in another state in the context of a TEIA procedure operated by another. Yet it has recently been argued that TEIA is not as effective as domestic EIA because an underlying reason for the success of domestic EIA is the administrative law context for its enforcement;7 in the international law sphere the absence of a comparable context suggests enforcement is less effective, with few opportunities for individual or NGO challenges.8 Treaty non-compliance procedures, especially the Compliance Committee (CC) of the Aarhus Convention, go some way to providing a forum to raise these matters, although they are not designed as a means of individual dispute settlement as such.9