The appeal sought to overturn a ruling which said shape alone did not determine the product
Chocolate-maker Nestlé had not had a break after nearly a decade of trying to trademark its four-finger shape.
Judges in the European Court of Appeal dismissed its attempt to have the shape of the four-finger bar trademarked, another setback for the food giant in a decade long battle.
In a ruling delivered on Wednesday, the court said Nestlé had not shown that its shape was a sufficient mark of distinctive character in all the countries it seeks a trademark.
It added: "Therefore, the court upholds the General Court's judgment in which the latter held that the acquisition of distinctive character by a mark that was initially devoid of inherent distinctive character must be shown throughout the EU, and not only in a substantial part of the territory of the EU, and consequently, although such proof may be produced globally for all the member states or groups of member states, it is not, however, sufficient that the party with the burden of providing such evidence produces only evidence that fails to cover part of the EU, even a part consisting of only one member state."
Nestlé had been able to prove the bar's distinctive character in 10 countries - Denmark, Germany, Spain, France, Italy, the Netherlands, Austria, Finland, Sweden, and the UK - but could not prove the same for Ireland , Belgium Greece and Portugal.
It is already protected in Australia, Canada and South Africa - but getting the same level in Europe has been difficult.
Judges also rejected their competitor Mondelez's case that Nestlé had not proved the bar's character in the first 10 countries.
Three months ago, a legal adviser told judges to reject the latest appeal.
This appeal sought to overturn a 2016 ruling which said shape alone did not determine the product, but customers were influenced by brand names.
Nestlé has faced several setbacks in the past, most notably from Cadbury but also Mondelez (which now owns Cadbury), which manufactures a similar looking four-finger bar in Norway called Kvikk Lunsj.
In 2006, the EU granted the trademark to Nestlé for the shape of the bars, but this was contested by Mondelez, and since then the court battle has gone back and forth between the two confectionery companies.
Nestlé first applied for the trademark for the shape of the bar without the addition of the Kit Kat logo embossed on the top in the UK in July 2010.
Court documents showed that in 2013, a UK examiner determined the trademark in question was "devoid of inherent distinctive character" and rejected the request.
Mondelez and Nestlé have often been locked in courtroom battles, with Nestlé blocking Cadbury's attempt to trademark their shade of Dairy Milk purple.