In a decision hailed by an environmental group as a historic victory, an Amsterdam court ruled Wednesday that Dutch national airline KLM misled consumers in statements about sustainable aviation in a case that accused the carrier of “greenwashing.”

Amsterdam District Court said in a statement that in some advertisements, that are no longer in use, KLM “makes environmental claims based on vague and general statements about environmental benefits, thereby misleading consumers.”

The court said that in other cases, “KLM paints an overly rosy picture of the effects of measures such as Sustainable Aviation Fuels (made from renewable raw materials) and reforestation.” The court said such measures “only marginally reduce the negative environmental aspects and give the wrong impression that flying with KLM is sustainable.”

In a reaction posted on X, formerly Twitter, one of the groups that filed the case, Fossielvrij NL, called the ruling “a historic victory over greenwashing by big polluters.”

Greenwashing refers to claims that aim to deceive the public about how environmentally friendly a product, policy or organization is.

The groups claimed that KLM violated European consumer law by misleading customers with ads and a carbon offset program that “give a false impression over the sustainability of its flights and plans to address its climate harm.”

The court did not order KLM to rectify the advertisements, and “does not have to warn consumers that current aviation is not sustainable.” But it said that if the airline “informs consumers about its ambitions in the area of CO2 reduction, for example, it must do so honestly and concretely.”

In a written reaction, KLM acknowledged: “Our communication about sustainability must be honest and transparent.”

“We are pleased that the court has ruled that we can continue to communicate with our customers and partners about our approach to making aviation more sustainable. We are continuously learning how best to include them in this,” it added.