Red. It’s Christmas and Coke. The color of communist dictators and conservative states. And it’s a primary color that, when slapped on the sole of a shoe, becomes a high-profile fashion lawsuit.

Last week, Paris-based footwear designer Christian Louboutin filed suit against rival luxury fashion house Yves Saint Laurent over the use of Louboutin’s trademarked red soles. In the complaint, Louboutin’s lawyers claim that Yves Saint Laurent’s red “Palais Pump” and “Palais Slingback,” with matching red soles, are “virtually identical” to his trademark — one so well known that “the lead characters regularly wore Louboutin footwear in ‘Sex and the City,’ ” Harvey I. Lewin of McCarter & English wrote in the suit.

The U.S. Patent and Trademark Office awarded Louboutin a registered trademark for the red soles in 2008. Louboutin is seeking an injunction against Yves Saint Laurent and damages that total $1 million, which may seem to be a small sum in a case that the fashion-industry bible Women’s Wear Daily is calling “the clash of the titans.” Yves Saint Laurent is a subsidiary of Gucci Group, part of the French-based multinational luxury-goods company PPR.

It has the makings of a classic French farce. Dueling French designers battle over suede stilettos. Mistaken identities. Even Barbie makes an appearance.

But the complaint — which includes lyrics by Jennifer Lopez and photos of Sarah Jessica Parker in a dress made of newspaper clippings — distracts from the larger issues at stake. Like the color, Louboutin’s “Red Sole Mark” is largely symbolic of a greater debate in trademark law as it relates to the fashion industry.

Should a designer be able to trademark a color?

“He has already trademarked the red sole. It’s fairly distinctive and associated with the brand,” said Anthony Dreyer, a partner at Skadden, Arps, Slate, Meagher & Flom and professor of trademark law at Fordham Law School. “He’s registered for the trademark the same way that Louis Vuitton trademarked the interlocking LV. But how strong is the trademark? Louboutin will have to show that customers or the public have been confused by Yves Saint Laurent’s replication of it.”

Dreyer says that in luxury markets, the discerning customer is rarely confused before he or she makes a purchase. Few customers will go to Neiman Marcus in search of Louboutins and mistakenly drop $1,125 on a pair of Yves Saint Laurent’s python pumps.

But Yves Saint Laurent, which would not comment on the lawsuit, potentially has an argument that highlights the purpose of trademarks and generates a flurry of existential questions concerning, yes, the nature of women’s shoes.

“In trademark law, you can’t protect something that is functional,” said Dreyer, who cited the textbook example of an orange safety vest. “One has to ask if the red sole serves a purpose in fashion.”

Does blending into red-carpet events constitute a sufficient function in a court of law?

Most likely, we’ll never know. Many trademark complaints in fashion end without litigation. In 2008, Diane Von Furstenberg Studio L.P. claimed Target infringed on its copyright by selling a Merona wrap dress in a print nearly identical to its “spotted frog” print. Target removed the design almost immediately.

It’s hard to glean whether retailers who carry both Louboutin and Yves Saint Laurent will do the same. A representative for Neiman Marcus stores, which carry both designers, declined to comment on how the lawsuit might affect the sales of either label.

Louboutin isn’t stopping at Yves Saint Laurent. This week, the company filed a second lawsuit against Sao Paulo-based Carmen Steffens of Brazil for shoes with “rosette” soles.

In an e-mail, Mark Willingham, president of Carmen Steffens’s U.S. operations, said that the company “is headquartered in a very tropical, exotic country” and “has been utilizing bright, fun colors in our product designs since its launch 18 years ago.”

The brand, which is being sued only in France, is relatively new there, having opened its flagship store in September adjacent to a Louboutin boutique on Rue de Grenelle. Of the 250 styles in Carmen Steffens France’s current collection, Willingham says three use shades of red. “Over the years, we have incorporated almost every color imaginable into our footwear soles including blue, green, pink, yellow. . . . This is what we are about.”

Like many farces, it’s possible this suit could end in success for all parties, with publicity for all.

Boyle is an editor at Express.