Christian Louboutin is going to a fashion show at Louis Vuitton Foundation in Paris, France, July 5, 2016. (Shutterstock/File)
French luxury shoe designer Christian Louboutin suffered a setback Tuesday in an EU legal battle over his signature red-soled high-heeled shoes.
Louboutin took Dutch shoe maker Van Haren to court in the Netherlands in 2012 after Van Haren sold similar women's shoes with red soles.
The Parisian designer said he had already trademarked the style in Europe in 2010 and 2013.
But Van Haren challenged the lawsuit and the Dutch court referred the issue to the European Court of Justice, the bloc's top court.
The chief advisor to the Luxembourg-based court, Advocate General Maciej Szpunar, backed Louboutin's opponent on Tuesday.
"According to Advocate General Szpunar, a trade mark combining colour and shape may be refused or declared invalid on the grounds set out under EU trade mark law," the court said in a statement.
He said it was possible such a trademark could be "unduly restricting" for other retailers "offering for sale goods or services of the same type."
The opinion is not binding on the ECJ but it often follows the thinking of the advocate general.
The EU opinion runs counter to that of a US court which ruled in 2012 that Louboutin could trademark his famous red soles.
It reversed a ruling that would have allowed rival Yves Saint Laurent to paint its outsoles scarlet.
Louboutin has marketed shoes with red outsoles since 1992.
The glam footwear was featured on the consumerism-worshipping television series "Sex and the City".