Honey that contains traces of pollen from genetically modified crops needs special authorization before it can be sold, the European Union’s top court said on Tuesday, in a judgment that could have widespread consequences on the bloc’s policy on genetically modified organisms, or GMOs.

The ruling from the European Court of Justice came after several Bavarian beekeepers demanded compensation from their government for honey and food supplements that contained traces of pollen from genetically modified maize.

The beekeepers had their hives close to fields where the Bavarian government was growing Monsanto’s MON 810 maize for research purposes.

The EU has strict guidelines on authorizing and informing consumers about foods containing GMOs, a policy that has caused problems for producers of genetically modified seeds such as U.S.-based Monsanto Co. that are used to much laxer rules in other parts of the world.

Environmental activists said, Tuesday’s ruling will force the 17-country European Union to strengthen the rules even further at a time they worried the bloc was dropping its zero-tolerance policy toward GMOs.

“This is a victory for beekeepers, consumers and the movement for GM-free agriculture in Europe,” Mute Schimpf, a food campaigner for Friends of the Earth Europe, said in a statement. “This ruling rewrites the rule book and gives legal backing to stronger measures to prevent contamination from the likes of Monsanto.”

Earlier this year, the EU approved rules to allow the import of animal feed contaminated with small traces of genetically modified crops, a move that was heavily criticized by environmental groups.