[WTO and International Trade Case Review Series No. 43] Mexico – Measures Concerning Genetically Engineered Corn: The intersection of free trade, food sovereignty, indigenous rights, and science

This paper analyzes the first Sanitary and Phytosanitary (SPS) dispute under the United States–Mexico–Canada Agreement (USMCA), which concerns Mexico’s measures restricting the use of genetically engineered (modified) corn under its 2023 Presidential Decree. The dispute highlights the tension between a Party’s regulatory autonomy to pursue food sovereignty, especially to protect human health, indigenous peoples’ rights, and biodiversity, and the obligation of Parties to ensure market access for GMO products under the USMCA. The principal issues in this case centered on Mexico’s obligations to base its SPS measures on an “appropriate risk assessment,” as well as its obligations regarding the “necessity” and “trade-restrictiveness” of the measures. Mexico further contended that its measures additionally serve non-SPS objectives and thus could be justified under the General Exceptions and the Indigenous Peoples’ Rights Exception. After reviewing the procedural background and the Parties’ main arguments, this paper critically assesses the Panel’s interpretations and findings on those legal issues. Notably, the findings under the SPS Chapter have weighed heavily against Mexico’s arguments for justification regarding its non-SPS objectives. This underscores the relevance of scientific explanations (e.g., risk assessment), as part of justification claims, within the context of the necessity test and the chapeau requirements, particularly in cases involving crucial scientific elements. Finally, as the Panel introduced notable interpretive approaches to some provisions that parallel WTO Law, this paper explores their implications for WTO dispute settlement jurisprudence.