The deregulatory nature of trade rules frequently brings them into conflict with the precautionary principle. These rules dominate debate over the content and legal status of the precautionary principle at the international level. The World Trade Organization (WTO), because of its power in settling disputes, is a key player. Many States are concerned to define the precautionary principle consistent with WTO rules, which generally means defining it as simply a component of risk analysis. At the same time, many States, especially environmental and public health policymakers, see the principle as the legal basis for preserving domestic and public health measures in the face of deregulatory pressures from the WTO. The precautionary principle has begun to acquire greater content and to move into the operative articles of legally binding international agreements. It is important to continue this trend.