If Converse is officially the most knocked-off shoe in the world, Christian Louboutin is hot on its heels thanks to a fresh development in its seemingly never-ending legal drama. Over the past several years, Christian Louboutin has sued brands from Yves Saint Laurent to Charles Jourdan for copying the bright red sole made famous by Louboutin in the '90s. The result of this litigiousness? Christian Louboutin now holds a valid trademark in the U.S. for its red sole — just so long as that red sole contrasts with the shoe's upper portion. In other words, an all-red pair of heels with a red sole (which were the subject of the YSL lawsuit ) are not considered a violation of Louboutin's trademark under U.S. law. That ruling helped to clarify things stateside, but has not stopped European brands from appropriating the red sole — something Louboutin has been working to change. The Fashion Law reports that Louboutin was back in court last week at the Court of Justice of the European Union (CJEU), the highest court in the E.U. legal system. At issue is Louboutin's 2013 suit against Dutch shoemakers Van Haren, which had stocked a red-soled style in its “5th Avenue by Halle Berry" collection. The court ordered the brand to cease production and sale of that shoe, but Van Haren appealed the decision in 2014 on the grounds that the red sole "lacks distinctiveness" which would associate it with a particular designer — and distinctiveness is one of the requirements for any trademark in Brussels. It's now up to the court to decide just how trademark-worthy that red sole is. Somehow, we have a feeling Louboutin won't give up without a fight — and that many ladies who lunch would be surprised to hear their beloved red soles are anything other than a distinctive mark of their shoes' pedigree. ( The Fashion Law