The efforts on the part of Monsanto to introduce Roundup Ready (RR) soybeans into Brazil have been impeded since 1998 by court action by IDEC (a consumer rights organisation) and Greenpeace. The lack of toxicological studies concerning the specific environmental impact on Brazil is the main argument against the marketing of genetically modified organisms (GMOs) in the country. Being unable to carry out such a rapid diffusion of GMOs in Brazil, which is the world's second largest exporter of soybeans, has caused great uncertainty regarding the outlook for further investment in this kind of technology. The objective of this paper is to analyse the process of regulation of GMOs as an explanatory variable of the pace and the direction of technical progress. It is used as an element for the analysis of Monsanto's strategies for obtaining fast approval of GMOs in Brazil, as well as the tactics of resistance adopted by Brazilian pressure groups. This dispute reveals a fundamental aspect of the firm selection environment that has not been sufficiently tackled in economic literature. Emphasis is given to the relationship between political power and economic power in the creation and implementation of laws and norms affecting the pace and direction of technical progress.