In the past two hundred years, there has been much concern with the Malthusian race between population growth and food supply. So far, food has won: increases in agricultural productivity have exceeded population growth. The last century saw three revolutions in agricultural technology — one based on mechanization, one on chemistry (leading to effective fertilizers and pesticides), and one on biology (the “Green Revolution”). For much of this period, agricultural productivity and output have grown rapidly and the relative price of food has declined. But the new genetic modification (GM) technologies that many expect will help the world meet its food needs — not only through quantity, but nutritional quality as well — raise critical issues for international trade, including this key question: What will happen if pressure from consumers and environmentalists in the developed world leads to a new generation of trade restrictions, or to the segmentation of GM-food product markets, as appears to be happening in Europe and Japan? An answer to this question requires a brief look at agricultural trade and involves both legal and economic analysis.