Environmental claims may only be used in advertising if they are clearly substantiated and "deception of the target public" can be ruled out. If the reference to the environmental friendliness of a product or service can be misunderstood, the advertising company is obliged to provide further clarification. When assessing whether advertising with environmental protection terms is likely to mislead, the courts apply a strict standard, similar to that for health advertising. This has been demonstrated in recent months in two cases brought by the VKI (Association for Consumer Information) on behalf of the Ministry of Social Affairs under the Unfair Competition Act. In one case, a beer was advertised on television and on the internet with the claim "brewed CO2-neutral". It was disputed in the proceedings whether malting was part of the brewing process. This was important because malting requires heat, which is obtained from natural gas (a fossil fuel). The court came to the conclusion that the brewery should have referred to this fact in its advertising. The second case concerned the advertising of a flight to Venice using sustainable aviation fuel (SAF). This advertisement was also qualified as misleading by the court. The airline failed to mention in its advertising that "the technical standards stipulate a maximum admixture of SAF to conventional kerosene of 5 percent".
In both cases, the court examined "how a reasonably well-informed and reasonable person interested in the product, who pays appropriate attention to the purchase of such products, would understand the disputed announcement". In both cases, the respective court came to the conclusion that important circumstances for the consumer were not mentioned in the advertising and that the advertising was therefore misleading within the meaning of the provisions of the UWG.
