ARTIST NOTE: While Fashion design in general is difficult to copyright, certain specific identifying features of a design can be trademarked, including color.
*Use caution when a color is an intigral part of your Trademark.*
THE NEWS (NY Times 2012): The United States Court of Appeals for the Second Circuit held that Christian Louboutin had a valid and enforceable trademark for the use of red outsoles, BUT only when the rest of the shoe was painted in a contrasting color.
*Colors can be trademarked, but a brand needs to take care of the specific way it is used and how it distinguishes it in a way where it can enforce keeping others from using it.