The adoption of the EU carbon border adjustment mechanism raises several questions of compatibility with World Trade Organization (WTO) rules. Although the European Commission is presenting this measure as a “purely environmental” measure, it is, in reality, a trade defense measure that aims to protect the competitiveness of European companies. This does not detract from the legitimacy of the Carbon Border Adjustment (CBAM). But it does shed light on the outdated nature of WTO law. Rather than looking at how to make the CBAM WTO-compatible, it is time for a deep reform of the rules of international economic law.