This monograph on the precautionary principle reviews the basic environmental declarations of the most important international environmental organizations (UNO/UNEP, EEC, OECD, Council of Europe) and bodies (ILA, IDI, ILC). It also analyzes the international agreements for the protection of the environment (water, land/species, air/atmosphere).;This analysis covers the basic documents of international environmental law issued from 1911 to 1993 and its aim is to specify the extent of establishment, and impact of, the precautionary principle in current international environmental law (customary law and conventions)