US genetically modified corn may return as a USMCA trade flashpoint
Mexico’s future rules for genetically modified corn could become a sensitive issue in the next USMCA negotiating round. US suppliers want secure access to Mexico’s market, while Mexican policymakers continue to emphasize native corn, food sovereignty and biosecurity.
Market access returns to the negotiating table
Mexico’s treatment of genetically modified yellow corn could become a central agricultural issue during the fourth round of negotiations under the United States-Mexico-Canada Agreement, according to El CEO. The dispute combines two closely connected questions: whether US corn will retain open access to the Mexican market and how Mexico will implement new domestic rules governing genetically modified grain.
The Wilson Center said that guaranteeing unrestricted access for US yellow corn and preventing new import barriers could be an important part of the talks expected at the end of the month. Mexico is one of the main destinations for US genetically modified corn. For Mexican buyers, the grain helps meet substantial demand from the livestock sector and is used primarily in animal feed and industrial applications.
Pending legislation creates regulatory uncertainty
Mexico’s Congress has yet to adopt secondary legislation implementing the 2025 constitutional reform on genetically modified corn. The Wilson Center warned that the unfinished legal framework could create future risks for import flows. The constitutional change, adopted during President Claudia Sheinbaum’s administration, provides for the use of genetically modified corn to be evaluated for possible threats to biosecurity, human health and Mexico’s biocultural heritage.
Washington is consequently expected to seek confirmation of several USMCA provisions during the fourth round. These include Chapter 2 on market access, Chapter 3 on agriculture and Chapter 9 on sanitary and phytosanitary measures. The same provisions were relevant in 2024, when a USMCA panel found that certain Mexican restrictions on genetically modified corn were inconsistent with the country’s treaty commitments. The Wilson Center said reaffirming the chapters would require any new Mexican regulation to comply with the trade agreement.
The earlier dispute remains unresolved politically
The controversy began under former President Andrés Manuel López Obrador, whose government issued a decree in 2023 establishing measures for the use of genetically modified corn. Its central restriction concerned the use of genetically modified corn in dough and tortillas. López Obrador argued that the measure was needed to protect native corn and public health from agrochemicals. The United States challenged the policy, arguing that it lacked a scientific basis and violated the USMCA, and the dispute proceeded to arbitration.
In December 2024, the USMCA panel overturned the import restrictions. US corn exports to Mexico continued the following year, but Mexico kept emphasizing native-corn protection and food sovereignty, according to the International Compliance Professionals Association. The association said the two governments still lack an agreement under which Mexico would formally commit to eliminating restrictions on genetically modified corn imports.
Rail inspections add a second obstacle
Regulation is not the only concern for US grain suppliers. Producers have also reported serious delays in shipping different grains to Mexico by rail, which they attribute to excessive inspections along rail routes. The American Soybean Association has asked for the issue to be included in the USMCA negotiations.
The talks therefore carry operational as well as legal implications. A confirmation of existing USMCA disciplines would support continuity for yellow-corn shipments used in Mexican animal feed. Unresolved secondary legislation or prolonged rail inspections could still raise uncertainty for farmers, traders, feed manufacturers and livestock producers on both sides of the border, even if no formal import ban is restored.
