1) Treaties, protocols, conventions, etc.
International environmental agreements are generally multilateral (or sometimes bilateral)treaties (a.k.a. convention, agreement, protocol, etc.). The majority of such conventions deal directly with specific environmental issues. There are also some general treaties with one or two clausesreferring to environmental issues but these are rare. There are about 1000 environmental law treaties in existence today; no other area of law has generated such a large body of conventions on a specifictopic.
Protocols are subsidiary agreements built from a primary treaty. They exist in many areas of international law but are especially useful in the environmental field, where they may be used toregularly incorporate recent scientific knowledge. They also permit countries to reach agreement on a framework that would be contentious if every detail were to be agreed upon in advance. The mostwidely known protocol in international environmental law is the Kyoto Protocol.
2) Customary international law
Customary international law is an important source of international environmentallaw. These are the norms and rules that countries follow as a matter of custom and they are so prevalent that they bind all states in the world. When a principle becomes customary law is not clear cutand many arguments are put forward by states not wishing to be bound. Examples of customary international law relevant to the environment include the duty to warn other states promptly about icons of anenvironmental nature and environmental damages to which another state or states may be exposed, and Principle 21 of the Stockholm Declaration ('good neighbourliness' or sic utere).
International environmental law also includes the opinions of international courts and tribunals. While there are few and they have limited authority, the decisions carry much weight...