In response to recent approval of a genetically-modified corn product by the European Union, nineteen out of the twenty-eight European Union member countries have decided to opt out of the use of that crop, effectively banning their use.

The list of European countries that have either opted-out of use of the EU-approved products, includes Austria, Bulgaria, Croatia, Cyprus, Denmark, France, Germany, Greece, Hungary, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Poland, and Slovenia. The United Kingdom requested for a partial opt-out, applied to Scotland, Wales and Northern Ireland, while Belgium applied for a ban for Wallonia.

At the heart of the issue is the European Commission’s approval of a form of genetically-modified corn, called "MON810 maize". However, many of the involved countries have also preemptively applied to also opt-out on other GM maize products that are still under EU review.

Many of these countries’ governments are making use of an opt-out provision in EU laws, that effectively allows them to block the cultivation of GM crops that were previously approved by the European Commission. This is essentially a method of requesting biotech companies to not sell the products in question within their countries; if the companies do not comply, this can lead to the countries that have not already issued outright bans to do so.

Common reasons given by the countries involved in the ban were concerns over consumer and farmer safety issues raised by recent health studies on GMO products; the potential impracticality of keeping GMO and non-GMO crops segregated; and maintaining the international reputation of their respective countries’ food exports.