In what is regarded as a final attempt to protect its red-sole trademark, French luxury brand Christian Louboutin has taken the case against YSL to the federal appeals judges.

Louboutin, the head designer and owner of the luxury brand, maintains that the use of the red soles by other designers might confuse consumers and may lower their brand value.

Sitting close to Louboutin was Belgian-American designer Diane von Furstenberg who reportedly came to lend moral support to her designer friend.

For YSL and PPR Group, this might just be a legal matter, but that's not the case for me. On the contrary, to me it is very personal: after all, this is an intrinsic part of my life and my company, which bears my name - and which I have built over the past 20 years and still independently own. This is why I had to be there in person, Vogue quoted Louboutin saying.

According to the Telegraph UK, the Louboutin case has divided the fashion world and gained interest from trademark lawyers and legal professors specializing in trademark issues.

It was in April last that the French footwear brand filed a trademark infringement lawsuit that charged YSL for breaching its copyright by using the red sole.

Mr. Louboutin is the first designer to develop the idea of having red soles on women's shoes. The defendants' use of red footwear outsoles that are virtually identical to the plaintiffs' Red Sole Mark is likely to cause and is causing confusion, mistake and deception among the relevant purchasing public, the lawsuit said, according to a Reuters report.

However, in their defence, YSL said that the red-sole trademark should not be given to any company as no brand should have the monopoly on color. They further mentioned that the use of red soles dated back to a long time and have been worn through the ages by many people.

Although a preliminary injunction by Louboutin to stop YSL from selling red-soled shoes were denied, the brand launched an appeal against the court's original decision. This dragged the case into 2012.