Abstract
Governments are increasingly using taxes to address a variety of environmental concerns. World Trade Organization (WTO) rules recognize that, like regulatory instruments, governments may use taxes for protectionist purposes. The rules are designed to prevent protectionist behaviour while allowing use of such instruments for genuine purposes such as environmental protection. Interestingly, however, there are some notable anomalies in the rules arising from differential evidentiary requirements in different situations. First, the rules are different depending upon whether a country's measure aims to protect on one hand human, animal, or plant health; or on the other, the environment. Second, the rules are stricter where a country's measure takes the form of a regulation than where it takes the form of a tax. The article argues that there is no principled rationale for the differential evidentiary requirements by instrument (regulation versus taxes) or area (health versus environment) but finds that there may be both a historical and political economy explanation. It also discusses the desirability for consistency in WTO law across instruments and risk-related policy areas.