In 2003, an act was approved to allow the cultivation of some genetically modified organisms-GMOs in Portugal.
In 2004, Algarve was the first region of the country to be declared as a free transgenic zone (this included 16 municipalities of the region and took place through the Association of Municipalities of the Algarve-AMAL). In 2005, an other act was approved to allow the coexistence of genetically modified varieties with conventional crops and with organic production. The possibility of this coexistence is questioned by several actors because of the risk of cross-contamination.
Only in 2007 a decree made it possible to establish free transgenic zones by farmers decision or municipal initiative, however the decision on the application for free zone establishment must have been approved by an absolute majority of the members present at the meeting of local municipal assembly. This decision didn't become universally accepted but became an important tool in opposition on GMOs.
In 2007, the existence of a transgenic maize production by Monsanto in Herdade da Lameira, in Silves, region of Algarve was denounced. The president of the Greater Metropolitan Area of Algarve-AMAL and the Association for Defense of Cultural and Environmental Heritage of Algarve-ALMARGEM positioned against this kind of crop. On August 17th, 2007, about 150 people organized into Movement Verde Eufémia and travelled to Herdade da Lameira to protest against the cultivation of transgenic crops and destroyed a culture of approximately 50 hectares. The act was supported by a Left Block Party-BE representative and environmental associations that together declared not to share the methods used by the Movement Verde Eufémia, but recognized the need to discuss and combat the planting of GMOs in Portugal. This action was criticized and criminalized by the national press, but helped to highlight the need to discuss the transgenic issue in the country. The Platform of Transgenic Out has been working on this issue since 1999. It is composed by associations, environmental groups and the agricultural sector. Its field of action includes activities such as workshops given by activists, protests in several events, participation in public bodies meetings, questioning government actions and decisions, conducting information sessions, lectures, conferences, awareness campaigns and debate among the population and public administration, dissemination of research, interventions in schools and universities, communications with farmers, supermarkets and consumers that produce and consume GMOs, etc. In 2013, for example, the ten largest Portuguese hypermarkets were visited in the cities of Lisbon and Porto to evaluate the food supply containing GMOs and information was available to consumers to do their shopping. In Portugal, the main issues involved the production, importation and consumption of GMOs and the resistance to this crop are: to combat the increasing maize transgenic plantation and give information about these crops, boycott the GMO foods consumption; support the campaign "free seeds" in articulation with the European movement, oppose the monopoly of seeds by multinationals; to fight and warn about the use of herbicides in public areas and the increasing use of herbicide with glyphosate. To these questions are added the free transgenic zone theme which several municipalities of Algarve and other 27 chambers in the continent were declared free zones. In 2011, the island of Madeira and Azores, in 2012, declared themselves GMOs free zones.