It sounds simple enough: Affirm that the food one buys has not been genetically modified. Require it on the nutrition label, right alongside the counts for cholesterol, sodium, carbohydrates, etc.
This is anything but simple. Counterintuitively, in fact, a GMO label will likely achieve the opposite of its purpose. How so? Right now, organic foods that are produced with every effort not to introduce genetically modified seeds or ingredients affirm the GMO-free process of production. What the GMO label demands, however, is something else: affirmation of a GMO-free food.