Nestlé has lost its decade-long battle to keep the trademark for the shape of its four-finger Kit Kat bar.

The ruling opens the door to competitors releasing similar products and own-brand versions.

The European Court of Justice (ECJ) claimed Nestlé had failed to show that Kit Kat’s shape has a ‘sufficient mark of distinctive character’ in the countries it intended to trademark in 2016. The transnational food and drink company won copyright for its bar in ten countries, with protection over Kit Kat’s shape already established in Canada, Australia and South Africa.

However, Nestlé failed to prove the shape was distinctive enough in Belgium, Greece, Portugal and Ireland.

Nestlé and the EU Intellectual Property’s office made an appeal against the ECJ’s decision, arguing against the need to prove the uniqueness of the bar. However, the court rejected their objections.

In 2006, the EU allowed Nestlé to acquire the trademark for the Kit Kat shape, much to American multinational company Mondelez’s dismay. The confectionary company also owns a four-finger bar in Norway called Kvikk Lunsj, a product that has existed for a slightly lesser time than Kit Kat, as well as Oreo, Milka, Leo and Cadbury.

Mondelez challenged this ruling, which triggered the battle between the two companies. The company also argued that Nestlé had not proven the Kit Kat bar’s character in ten countries, however judges threw out its case.

Nestlé has also attempted to block Cadbury’s trademark of its shade of Dairy Milk purple.

The ECJ now says proving a product’s significance in a particular part of the EU isn’t enough. Products have to be proven across all markets of the bloc.

Mondelez, which owns triangular-shaped chocolate bar Toblerone, has been successful in trademarking its shape.