Swiss food giant Nestle has failed in a bid to get the EU's top court to let it trademark the shape of its four-fingered Kit Kat chocolate bar in Britain.
The European Court of Justice said Nestle had to prove consumers could identify the wafer snack by its appearance alone - without markings or labels bearing the Kit Kat name.
It referred the case back for a final ruling to Britain's High Court, which had thrown out the trademark application in 2013, following an appeal by rival confectioner Cadbury.
"It is up to the British courts to decide, on the basis of this response, if the form of Kit Kat chocolate bars can be registered as a trademark or not," the EU court said in a statement on Wednesday.
Nestle had argued that the shape of the famous snack - which was first sold in 1935 and is marketed with the slogan "Have a Break, Have a Kit Kat" - was in itself distinctive.
The case has dragged on for five years after Nestle filed the trademark application in 2010 and Cadbury appealed the following year.
The EU judges noted that the trademark Nestle is seeking differs from the actual product because it shows only a picture of the bar and omits the embossed word "Kit Kat" and sections of its oval logo.
They also said that some of the features of the bar's shape resulted from technical processes, not design.
"The trade mark applicant must prove that the relevant class of persons perceive the goods or services designated exclusively by the mark applied for, as opposed to any other mark which might also be present, as originating from a particular company," it said in its ruling.