In light of the recent EC – Seal Products dispute in the WTO involving the public morals exception of GATT XX(a), this thesis aims at finding criteria to delimit the scope of this concept, to prevent that WTO Members could justify largely any trade measure under this exception. To this end, insights from a comparison to the GATT National Security exception, and from the European Court of Human Rights’ assessment of its morals exception are sought and applied to the analysis of GATT XX(a). This thesis finds that the most appropriate way to delimit the scope of ‘public morals’ is within the necessity test of GATT XX(a). In a process of ‘weighing and balancing’ under the necessity test, it should be considered whether consensus among WTO Members exists, notably through international agreements, which evidences the concrete necessity of a measure to justify on moral grounds a violation of international trade law.