Most organic farmers are aware that they may not plant genetically modified organisms (GMOs), or seeds developed through genetic engineering, if they wish to market their crops as organic. Yet many organic farmers have questions about their legal rights and responsibilities with respect to the unintended presence of GMOs. These questions relate to two basic interests of organic farmers: maintaining their organic certification and meeting the requirements of their buyers.

This article examines requirements to avoid the use of genetic engineering that affect crop and livestock farmers who are certified organic, or who wish to become certified organic. The article also briefly addresses handling requirements as they apply to organic farmers. The article is concerned primarily with issues related to organic certification, but it concludes with a brief discussion of the ways in which sales contracts may impose responsibilities upon farmers that differ from the requirements for organic certification.