In a unanimous judgment, the court held that Swedish oat drink company Oatly’s attempt to trademark the slogan “Post Milk Generation” was unlawful. The justices concluded that protected dairy terminology cannot be used in ways that risk confusing consumers about the nature of a product.

The decision is expected to reverberate across supermarket shelves, where plant-based drinks have grown rapidly in market share. Industry analysts said brands may now rely more heavily on descriptions such as “oat drink” or “plant-based drink”, rather than language historically associated with animal-derived dairy.

Oatly expressed frustration at the outcome, arguing the ruling created “unnecessary confusion” and favoured “Big Dairy”.

The case arose after Oatly sought to register “Post Milk Generation” as a trademark for merchandise and a range of oat-based goods. Dairy UK, representing milk producers, opposed the application, contending that it breached regulations reserving the term “milk” for products of animal origin.

For consumers, the practical effect is likely to be seen in packaging rather than pricing. Legal and branding specialists said the ruling provides firmer guidance in a sector that has often drawn on dairy vocabulary to signal taste and usage. While most shoppers recognise that oat and almond products are dairy-free, regulators have increasingly insisted that established food terms retain precise definitions.

Brands may now be forced to adjust labels and marketing strategies to avoid relying on dairy shorthand.

Bryan Carroll, general manager of Oatly UK & Ireland, said: “In our view, prohibiting the trademarking of the slogan ‘Post Milk Generation’ for use on our products in the UK is a way to stifle competition and is not in the interests of the British public.”

Judith Bryans, chief executive of Dairy UK, said: “We are delighted. This ruling is an important decision for the sector as it finally provides clarity on how dairy terms can — and cannot — be used in branding and marketing.

“It brings greater certainty for businesses and helps ensure that long-established dairy terms continue to carry clear meaning for consumers, while allowing appropriate descriptors to be used where the law permits.”