Like many other branches of international law, international environmental law is interdisciplinary, intersecting and overlapping with various other areas of research, including economics, political science, ecology and human rights.  It is the body of international law that deals with the protection of the global environment.  Originally associated with the principle that a state should not use its territory in such a way as to injure the territory of other state, international environmental law has since been expanded by various international agreements.

The main sources of international environmental law are international agreements, customary international law and general principles of law, case laws, doctrines and resolutions.  The international environmental law provides legally binding international agreements which covers various areas like atmospheric, terrestrial and marine ecosystems, biodiversity, and wildlife.

The first United Nations Conference on the Human Environment (UNCHE) held in Stockholm 1972 emphasized that defending and improving the environment must become a goal to be pursued by all countries.  Following this conference, the United Nations Environmental Programme (UNEP) was launched in order to encourage United Nations agencies to integrate environmental measures into their programs.  In 1987, Brundtland Report, from the United Nations World Commission on Environment and Development (WCED) was published that coined the phrase sustainable development for the first time.

The 1992 Rio conference (earth summit) led to the adoption of many important environmental treaties such as the 1992 United Nations Framework Convention on Climate Change and the 1992 Convention on Biological Diversity.  Transfrontier pollution, marine pollution, endangered species, desertification, climate change, hazardous materials and activities are some of the other environmental areas that are protected by various conventions.