In order to help prevent contamination of conventional crops by transgenic crops, the European Commission has drawn up guidelines on the co-existence of genetically modified, conventional and organic crops (Commission Recommendation 2003/556/EC on guidelines for the development of national strategies and best practices to ensure the co-existence of genetically modified crops with conventional and organic farming - OJ L 189, 29 July 2003).

The Commission has left the Member States the possibility of adopting measures to avoid the unintended presence of GMOs in conventional products. However, the primary responsibility for avoiding contamination lies with operators.