The World Trade Organization (WTO) and its predecessor the General Agreement on Tariffs and Trade (GATT) have been extraordinarily successful at liberalizing trade in the global economy. The process of liberalization has entailed a series of negotiations resulting in reciprocal commitments to reduce or eliminate tariffs, quotas and other traditional instruments of protectionism. To ensure the integrity of those commitments, it has been necessary since the inception of GATT to prohibit member nations from substituting other protectionist devices for those which they promise to forego.

Domestic regulations, in particular, can disadvantage or exclude foreign suppliers from export markets. Such regulatory obstacles to exports are known as “technical barriers to trade.” A number of legal principles have evolved in the WTO system to discipline technical barriers. Regulations that discriminate against foreign suppliers are the most obvious source of undesirable technical barriers, and WTO law imposes an obligation on the regulators of member nations to avoid discrimination that disfavors foreign suppliers. Facially nondiscriminatory regulations that impose relatively greater compliance costs on foreign suppliers can have the same effect as discriminatory regulations, however, and WTO law thus includes an array of constraints on domestic regulation that go beyond simple nondiscrimination requirements.

One such constraint may be termed a “scientific evidence requirement” – a requirement that certain regulations, generally those enacted for the purpose of protecting health, safety or the environment, be based on scientific evidence.