Petitioner KP Permanent Make-Up, Inc., and respondents (collectively Lasting) all use the term "micro color" (as one word or two, singular or plural) in marketing permanent cosmetic makeup. The Court accepts KPs claim that it has used the single-word version since 1990 or 1991. In 1992, Lasting registered a trademark that included the words "Micro Colors" under 15 U. S. C. §1051, and, in 1999, the registration became incontestable, §1065. When Lasting demanded that KP stop using the word "microcolor," KP sued for declaratory relief. Lasting counterclaimed, alleging, inter alia, that KP had infringed Lastings trademark. KP responded by asserting the statutory affirmative defense of fair use, §1115(b)(4). Finding that Lasting conceded that KP used "microcolor" only to describe its goods and not as a mark, the District Court held that KP was acting fairly and in good faith because KP undisputedly had employed the term continuously from before Lasting adopted its mark. Without enquiring whether the pra