On October 19, the United States and Mexico announced that they had formed a panel to review an ongoing dispute over corn. Though drug trafficking and migration tend to take center stage in the relationship between the two countries, for months, they have been engaged in another type of conflict—a food fight.

In 2021, Mexico’s Supreme Court outlawed genetically modified corn seeds, constitutionally enshrining the argument that genetically modified organisms (GMOs) permanently damage biodiversity, that genetic diversity within crops is indispensable for responding to climate change, pests, and disease, and that corn’s diversity in particular is vital to food security for Mexico and the globe alike. In February of this year, the country followed the ban with a decree outlawing GMO corn for human consumption.

In response, the U.S. has argued that Mexico is violating the updated North American Free Trade Agreement, or NAFTA, now called the United States-Mexico-Canada Agreement (USMCA). Trade officials, Congress, and lobbyists from the U.S. and Canada, anxious over the prospect of lost exports, have painted Mexico’s decree as protectionist and emotional. But Mexico’s insistence on its right to regulate GMOs isn’t just about corn. It’s a major step for rolling back free trade’s homogenization of farming, food, and culture worldwide.

GMO foods became commercially available in 1994, the year that NAFTA took effect. In GMO crops, genetic material from a different organism is inserted into a host plant’s DNA. Biotech firms use the technology to produce desired traits in crops, such as resistance to pests or chemical herbicides.

The overwhelming majority of U.S. corn is genetically modified. GMO methods typically increase harvest outputs, and have helped the U.S. become the world’s leading producer and exporter of the grain. Simultaneously, free trade policies that favor GMO crops have turned Mexico—corn’s place of origin and the center of its genetic diversity—into one of the world’s largest importers of the grain.

Mexico has at least 59 distinct corn races, providing genetic reservoirs that are unmatched anywhere else in the world. For Mexicans, maíz (corn) is the most important food item for calories and household budgets. Maíz is central to tamales, pozole, huaraches, and more, but its importance also goes beyond meals. Corn is a cultural inheritance. Indigenous communities see it planted into origin stories like the Mayan text Popul Vuh and represented in Aztec gods like Cintéotl, who rose from under the ground to protect maíz.

In 1994, however, NAFTA eliminated tariffs protecting Mexican corn farmers, arguing that everyone would benefit from lower-priced U.S. corn.

The reality was different. After NAFTA was enacted, nearly 5 million Mexican farmers—most of whom grew at least some corn—lost their rural livelihoods. At the same time, the agreement opened the door for processed imported corn products in junk and fast food, causing dramatic rises in obesity and diabetes.

Then, in 2006-2007, corn prices skyrocketed when energy markets drove up demand for ethanol, the corn-based energy source, to offset high oil prices. Because Mexico was reliant on imported corn by this time, the country experienced a “tortilla crisis,” with consumer prices for the staple spiking.

The GMO ban was put in motion in 2021, when Mexican president Andrés Manuel López Obrador announced a phase-out of GMO corn, to be effective by February 2024. Conceding to U.S. pressure, this year’s decree limited its ban to corn for human consumption, such as that used for tortillas or masa (dough). Mexico will still import corn-based animal feed, the primary American export, and can still import other GMOs, like cotton and canola.

In their ongoing and aggressive opposition to the decree, U.S. trade and agriculture officials have argued that there is no scientific basis for banning GMO corn. But the truth is there is no international consensus on GMO safety.

For years, Mexican scientists have raised concerns about multiple types of dangers from GMO corn. For instance, recent research found significant amounts of glyphosate—a herbicide used to farm GMO crops that a World Health Organization agency has determined likely causes cancer—in the urine of Mexican children, including newborns. This is expected to be from consuming GMO corn, either through direct consumption or exposure to the mother’s diet through breastfeeding.

The scientists have also shown that GMOs damage the plants themselves. GMOs disrupt plants’ natural growth processes and their gene sequencing, which determine their morphology and physiology. Because corn is fertilized through open-air pollination, it’s particularly vulnerable: just a light breeze can blow pollen from GMO plants into fields of non-GMO corn, or maíz nativo. Recent plant gene and data research into maíz nativo has shown that the non-GMO crops now have a reduced capacity to respond to threats like drought and invasive species.

Even as Mexico believes it has good reasons for outlawing GMOs, the U.S. says it does not have the right to do so. But there are multiple legal avenues for Mexico to argue that its ban is allowable under the USMCA.

First, the free trade agreement does not require Mexico to import GMOs. Chapter 3 expressly states that the agreement does not mandate any “authorization for a product of agricultural biotechnology to be on the market.” Second, Mexico can point to the treaty’s allowance for domestic controls over food safety. Chapter 9 allows each country to adopt measures it “determines to be appropriate” for “protection of human, animal, or plant life or health.”

Finally, Mexico can point out that Chapter 24 specifies that environmental issues—including “conservation and sustainable use of biological diversity”—are matters of national sovereignty.

In fact, environmental controls were one of the key selling points for the trade treaty to be approved by U.S. Congress. American legislators worried that if Mexican businesses did not comply with environmental regulations, such as over clean air or clean water U.S. exporters would be undercut.

Unfortunately, in the current dispute, the trade pact’s environmental clauses risk being subject to a double standard, with enforcement sought when environmental protections serve U.S. exports but ignored when they seek to safeguard access to a daily staple and maintain the health and safety of Mexican people.

But even as the countries treat these issues as questions of national sovereignty and economics, the ability to regulate GMOs is also of global concern. Corn is the world’s most grown crop, and maintaining its genetic diversity is crucial for food security worldwide: If a bacteria or fungus evolves to wipe out GMO corn, for instance, it’s crucial that there are other strains still available to grow. To preserve the biodiversity of corn—and of other crops—trade agreements must allow governments to craft and enforce policies that promote sustainable farming and safe food.

In this light, Mexico’s decree is an example for trade officials worldwide. After three decades of prioritizing commerce, it’s time to prioritize other aspects of cross-border coexistence and conviviality, like biodiversity, food security, and public health.