The United States is the leading country in the application of biotechnology to agricultural methods. One of the principal reasons for this is the flexibility of its legislation on Genetically Modified Organisms (GMO). A significant part of its production of soya or corn is already genetically modified, so that its companies need to avoid technical barriers to their exports in the world markets. In the EU, negative public opinion has contributed to the adoption by the authorities of exigent legislation in order to avoid the possible risks to human health and the environment posed by GMO. The EU's authorisation procedure for these organisms is long and meticulous. Furthermore, a compulsory labelling system has been adopted for products, which contain GMO or genetically modified materials (GM materials). In 1998, American interests started to be adversely affected by European legislation. The USA Administration threatened to sue the EU before the World Trade Organisation (WTO). These threats have yet to be followed up with any action. The rules of international trade are regulated by agreements signed up to by the members of the WTO. The EU can argue that its authorisation procedure is designed to reduce the risks to health and the environment. This line of argument is compatible with the Agreements on Sanitary and Phytosanitary Measures (SPS) and Technical Barriers to Trade (TBT). The compulsory labelling system is also compatible with the Agreement on TBT if the WTO accepts that a product in which GM material is detected is not similar to a conventional one. The Protocol of Biosafety further supports the EU position since it advocates a cautious approach exemplified by the fact that the Protocol permits consideration of non-scientific risks during risk assessment. However, the Protocol is not yet in force, it is pending ratification by at least 50 countries and, now more than ever, it is uncertain whether the United States will be willing to ratify the Protocol. However, we cannot be sure that there will be future commercial controversy, which will show the contradictions between the commercial agreement and the environmental one.