McDonald's has lost its rights to the trademark "Big Mac" in an EU ruling in favour of Ireland-based fast-food chain Supermac's.
The judgment revokes McDonald's registration of the trademark, saying that the world's largest fast-food chain has not proved genuine use of it over the five years prior to the case being lodged in 2017.
McDonald's was not immediately available to comment on the decision, which it can still appeal against.
The ruling allows other companies as well as McDonald's to use the "Big Mac" name in the EU.
Supermac's said it can now expand in the UK and elsewhere in Europe.
It said it had never had a product called "Big Mac" but that McDonald's had used the similarity of the two names to block the Irish chain's expansion.
"Supermac's are delighted with their victory in the trademark application and in revoking the Big Mac trademark, which had been in existence since 1996," said Supermac's founder Pat McDonagh.
"This is a great victory for business in general and stops bigger companies from 'trademark bullying' by not allowing them to hoard trademarks without using them."
McDonald's, which sells its flagship "Big Mac" burgers internationally, submitted printouts of European websites as evidence as well as posters, packaging and affidavits from company representatives attesting to "Big Mac" sales in Europe.
The Spain-based EU Intellectual Property Office (Euipo) said the affidavits from McDonald's needed to be supported by other types of evidence and that the websites and other promotional materials submitted did not provide that support.
From the website printouts "it could not be concluded whether, or how, a purchase could be made or an order could be placed", said Euipo.
"Even if the websites provided such an option, there is no information of a single order being placed."
McDonald's has historically been extremely litigious in the area of trademark law and typically does not lose.
In 1993 it won a court order blocking a dentist in New York from selling services under the name "McDental".
In 2016 it defeated an effort by a Singapore company to register MacCoffee as an EU trademark.
Reuters..