Trade treaties have introduced the principle that similar risks should be treated similarly, and that countries must achieve internal consistency in the levels of protection they afford against certain hazards within their territories. The problem is that there is no agreement on when risks are "similar" or when levels of protection are "consistent." The danger is that in resolving these issues, international trade institutions will infringe on the political sovereignty of their Members. This Article proposes a science-based solution. A substantial body of scientific research establishes that a person's judgments about the risk posed by a hazard are influenced by a number of factors, including certain characteristics of the hazard itself, scientific uncertainty in the evidence about the risk, and certain characteristics of the person evaluating the risk. This Article argues that such factors should also be relevant to deciding whether a country is being consistent in setting its levels of protection. International trade institutions that ignore such factors imperil their own success and legitimacy, and do so unnecessarily. General and specific empirical studies can provide a neutral means of deciding whether different levels of protection are risk-based or are merely disguised restrictions on international trade.