Comparative advantage which motors free trade crucially depends on national differences in respect of endowment with resources – e.g. natural,human, technological – and with factors and standards of production, including standards on production processes. Yet, is it open to any GATT contracting party to unilaterally force its own standards upon others?Moreover, is it permissible for a contracting party to enforce such standards by means of ‘trade sanctions’ in the form of import prohibitions against another whose environmental standards regarding certain production processes it has judged inferior to its own? The answer is a resounding ‘yes’ from some exponents of the environmental constituency, arguing that values pertaining to global environmental welfare should prevail. Similarly, some members of the GATT constituency, particularly developing countries, emphatically reject what it they term ‘eco-imperialism’.Generally, their argument is that, in order to safeguard the welfare of world trade against disguised protectionist aberrations, governmental environmental measures must be justified under the general exceptions of GATT.