This chapter examines the development of standards in the context of the environmental human rights guaranteed under the Aarhus Convention. Three procedural rights (the right to information, the right to participate in decision making and the right of access to justice in environmental matters) are presented in the Convention as underpinning the right of every person of present and future generations to live in an environment adequate to their health and well-being. The chapter considers how the Aarhus Convention Compliance Committee and the Court of Justice of the European Union interpret obligations arising under the Convention and develop criteria by which to assess compliance. Drawing specifically on the obligation to provide the public (including non-governmental organisations) with access to justice that is ‘not prohibitively expensive’, the chapter demonstrates the practical difficulties involved in articulating precise standards when obligations are articulated in general terms in an international treaty. It confirms the fundamental importance of accessible and effective review mechanisms to address any uncertainty over the scope of Convention obligations in a timely fashion. Such review mechanisms are essential if minimum standards are to evolve progressively and become embedded more deeply in national legal and administrative systems.