Last year, the luxury brand won the right to exclusively use its trademark of a red sole, but the New York appeals court urged the USPTO to further define the trademark to include a "contrasting upper," or the attached part of the shoe.
Louboutin further wants to change the language to include a red sole “that contrasts with the color of any visible portions of the shoe."
"YSL intends to oppose the relief sought by Louboutin because, if granted, it would have serious anti-competitive effects not only for YSL, but also for all other legitimate competitors who design and sell non-infringing women's footwear with red outsoles," David Bernstein, a lawyer for YSL wrote to the court.
The USPTO wrote late last month that it might not have the authority to make the changes without permission from the court that upheld Louboutin's original trademark. The parties have until this month to get further word from the New York court.
The actions stem from a Louboutin lawsuit against YSL for making an all-red shoe that included an all-red sole, claiming that it had violated the designer's trademarked design. While a District court said that a trademarking a single color would inhibit competition in the fashion industry, an appeals court struck down the decision.
By "deliberately tying that color to his product, Louboutin has created an identifying mark firmly associated with his brand which, 'to those in the know,' 'instantly' denotes his shoes' source," the court wrote in its decision.
Louboutin, which also makes handbags, men's shoes and accessories, says the red soles have been an identifying mark of the company since 1992. It was officially trademarked in 1998.