Introduction

This chapter identifies the sources of international legal obligation in the field of the environment, and the regulatory techniques used to give effect to these obligations. International law is traditionally stated to comprise ‘the body of rules which are legally binding on states in their intercourse with each other’. These rules derive their authority, in accordance with Article 38(1) of the Statute of the International Court of Justice (ICJ), from four sources: treaties, international custom, general principles of law, and subsidiary sources (decisions of courts and tribunals and the writings of jurists and groups of jurists). It is to these sources that the ICJ would look in determining whether a particular legally binding principle or rule of international environmental law existed. The list of sources identified in Article 38(1) does not wholly reflect the sources of obligation, broadly understood, which have arisen in international environmental law.