In approximately 1990, KP Permanent Make-Up, Inc. (KP) (plaintiff) began using the term “microcolor” in its sale of permanent makeup. Lasting Impression I, Inc. (Lasting) (defendant) registered the mark “microcolor” with the U.S. Patent and Trademark Office in 1993. Lasting’s registration achieved incontestable status in 1999. KP brought suit against Lasting seeking a declaratory judgment that its use of the mark was not infringement. Lasting brought a trademark infringement counterclaim, which KP defended on the grounds of fair use. The United States District Court for the Central District of California granted KP summary judgment on the counterclaim. The United States Court of Appeals for the Ninth Circuit (Ninth Circuit) reversed, finding, among other things, that KP did not carry its burden of negating any likelihood that its use of the mark would confuse consumers about the origin of the makeup. The United States Supreme Court granted certiorari.