Designer Christian Louboutin can claim trademark protection for the red outsole on his women’s shoes, but not if the rest of the shoe is also red, a federal appellate panel ruled yesterday, allowing rival Yves Saint-Laurent to continue selling an entirely red shoe.

The U.S. Court of Appeals for the Second Circuit in Christian Louboutin v. Yves Saint Laurent America, 11-3303-cv, rejected Southern District Judge Victor Marrero’s (See Profile) holding that a single color could never be trademarked when it serves as an element of fashion design. Judge José Cabranes (See Profile) wrote the decision, joined by Judges Chester Straub (See Profile) and Debra Ann Livingston (See Profile).

Christian Louboutin claimed that its trademark for red-soled shoes, above, was violated by Yves Saint Laurent’s entirely red shoes.