The shape of Nestle's four-finger KitKat bar has lost its EU-wide protected trademark status after the European Court of Justice (ECJ) dismissed an appeal by the confectionery giant.
Judges sitting in the Luxembourg court dismissed an appeal by Nestle against an earlier ruling that the company had only provided evidence that the chocolate was sufficiently well known in Denmark, Germany, Spain, France, Italy, the Netherlands, Austria, Finland, Sweden and the UK.
They had earlier been instructed that the chocolate was not well enough known in Belgium, Ireland, Greece and Portugal.
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They ruled that the EU Intellectual Property Office (EUIPO) must now reconsider whether the three-dimensional shape of the bar can be retained as an EU trademark.
If Nestle is unable to demonstrate that the KitKat has acquired distinctive character through use throughout the EU it will not get a trademark.
A General Court ruling in 2016 said that Nestle had to prove a Kit Kat was recognisable in every EU country.
The ECJ found that the General Court was right to annul the European Union Intellectual Property Office's (EUIPO) 2006 decision that "distinctive character had been acquired" without "adjudicating on whether that mark had acquired such distinctive character in Belgium, Ireland, Greece and Portugal".
It said: "On the basis of those considerations, the Court dismisses the appeals of Nestle and EUIPO."
Nestle has not sought such a status for its two-finger bar.
It follows a decision by appeal judges in the UK in favour of stripping KitKat of its UK-only trademark on the basis that the three-dimensional shape of a chocolate product had "no inherent distinctiveness".
The appeal court heard then that Nestle had spent between £3 million and £11 million a year advertising and promoting KitKats between 1996 and 2007.
More than 40 million were sold in Britain in 2010.
Mondelez International, previously known as Cadbury Schweppes, filed the original challenge to the EU trademark in 2007, a year after it had been granted.
Duelling between the two companies has also seen Nestle challenge Mondelez's British trademark for the shade of purple wrapper on its Cadbury's Daily Milk chocolate bars.
Toblerone, which is owned by Mondelez, has successfully trademarked its 'zigzag prism' shape.