This summer, in one of the most interesting rulings I've covered, Manhattan federal judge Victor Marrero likened the shiny red-enamel soles of Christian Louboutin shoes to John Deere's green tractors. Louboutin's red soles -- which made his sky-high heels (with equally sky-high pricetags) instantly recognizable to the fashion cognoscenti -- served an aesthetic purpose beyond mere function, Marrero concluded, just as the color green does for farm equipment. Colors can be trademarked, the judge found, only when they're used to identify a product and serve no other purpose, as in, for example, Owens Corning's pink fiberglass insulation. Marrero ruled that the U.S. Patent and Trademark Office goofed when it issued Louboutin a trademark on red soles in 2008. Yves Saint Laurent, he found, is free to sell shoes with red soles.

On Tuesday, Louboutin's lawyers at McCarter & English filed a brief at the U.S. Court of Appeals for the Second Circuit that lays out the many ways they believe Marrero abused his discretion in toppling one of fashion's most recognizable trademarks. "The sweeping per se rule announced by the court below is legally erroneous and must be reversed, because it violates the Lanham Act and controlling precedents of the United States Supreme Court and of this court," the brief said. "It is equally defective because there is no evidentiary support in the record below for the purported factual findings on which the lower court based its per se rule."

Louboutin's lead counsel, Harley Lewin of McCarter, told me Wednesday that Marrero reached his key conclusion -- that permitting fashion designers to trademark colors would hinder competition -- on an undeveloped record. "In our view there was no basis to make that finding," Lewin said. "Judges are supposed to base their rulings on the record before them.'It might' is not the analysis you use."

In the 20 years since Louboutin began using red soles, Lewin argued, there's been no shortage of competition in the marketplace for high-end women's shoes. And particularly because the red sole is "a world famous brand identifier," in the words of the McCarter brief, Marrero was wrong to hypothesize that any limit on a fashion designer's ability to use a color is an encroachment on competition.

"The court's diktat that a single color on a fashion item may not serve as a trademark constitutes an error of law," the brief said. "Color is protectable as a trademark unless it is essential to the use or purpose of the article, or affects its cost or quality. Louboutin's red outsole mark fits neither requirement. By putting a distinctive red color on the previously ignored bottom portion of the shoe, Louboutin established a strong brand identifier. The red outsole has no [other] utility."

McCarter's brief likened Louboutin's red soles to Tiffany's blue boxes, which are trademarked, calling Marrero's line between fashion and industrial uses of color "a distinction without a difference."

"Judge Marrero gave no credit for the most important thing -- the public," Lewin told me. "The argument should be framed from the perspective of the consumer. Does the consumer see the red sole as a source identifier?" (IP litigator Randy Lipsitz of Kramer Levin Naftalis & Frankel, who is not involved in the Louboutin litigation, agreed with Lewin: "The U.S. Supreme Court has said that in specific situations, color can function as a trademark," he said. "This is a unique situation. Louboutin has been using the mark for years, and it has extreme secondary meaning.")

David Bernstein of Debevoise & Plimpton, who represents Yves Saint Laurent, referred me to a company spokesperson who was not available for comment.

(Reporting by Alison Frankel)

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