Public morals are generally referenced in the form of grounds for an exception in multilateral trade agreements. As such, World Trade Organization (wto) member states can evoke the necessity of protecting public morals to justify domestic measures otherwise inconsistent with their obligations. Such a necessity has been evoked and interpreted by wto judicial bodies a number of times. The purpose of this study is to look at how the wto’s interpretation of the notion of public morals has evolved in terms of the interpretive methods provided for in the Vienna Convention on the Law of Treaties, particularly in Article 31(3) c). A study of dispute rulings shows that interpretations initially allowed member states wide latitude in determining what constituted public morals. Subsequently the test of public morals proposed in the report on the dispute European Communities — Measures Prohibiting the Importation and Marketing of Seal Products at first seemed to help clarify how the notion of public morals might be interpreted, but application of the test to the facts cast doubt on its actual methodological significance. It therefore appears that this most recent dispute must be considered a missed opportunity for the wto to demonstrate that trade law doesn’t operate in a vacuum.