In July 2000, Larry Bohlen, a senior official of the environmentalist group Friends of the Earth, went to his local supermarket in Silver Spring, Maryland, where he purchased chips, tacos, and “all the [other] corn products I could find.” He had a laboratory analyze them to determine if they contained any corn that had been genetically modified, or genetically engineered. The laboratory found that taco shells made by Kraft and sold under the brand name of Taco Bell contained traces of a type of genetically altered corn called Starlink. The Environmental Protection Agency (EPA), one of three government agencies in the United States that regulates genetically modified products, had approved Starlink for animal feed but not for human consumption. The Food and Drug Administration (FDA), which regulates the purity of foods, had not approved it either.

Friends of the Earth and another group called Genetically Engineered Food...