International environmental law (‘IEL’) began to emerge as a distinct subdiscipline of international law in the 1970s. Since then, it has assumed critical importance in helping to maintain the ecological systems upon which all life on planet Earth depends. It is continuing to develop and is relevant to all states and communities, affecting a wide range of human activities and concerns. This chapter briefly traces the history of IEL and sets out some recent institutional and policy developments, including the United Nations Environment Assembly and the UN Sustainable Development Goals. It also looks at concerted attempts to fill gaps in the field. Given the vastness of the subject matter, the chapter does not purport to be a comprehensive or in-depth analysis. It addresses the main organising principles of IEL, both established and emerging. It provides an overview of treaties (also referred to as multilateral environmental agreements or ‘MEAs’) in several key subfields, including regimes addressing the atmosphere, transboundary pollution, chemicals and wastes, biodiversity, and land degradation. It also includes a case study on world heritage and its implementation in Australia.

This book addresses multiple perspectives on challenges and solutions to the environmental rule of law for oceans. Despite the variety of perspectives, topics and geographical areas covered, several cross-cutting challenges appear. These include the need for both flexibility and generality, as well as both specificity and fit-for-purpose law; a lack of clarity in definitions, provisions and laws; the urgent need for enhanced coordination and cooperation; and the need to improve implementation, compliance and enforcement. This closing chapter presents solutions in the context of (1) tackling existing and new pressures on the marine environment, (2) ensuring a proper balance between exploitation and protection of oceans and seas, (3) improving implementation, compliance and enforcement and (4) strengthening the rule of law in regional seas and oceans.