L’Oreal USA (defendant) first used its “Shades EQ” mark in 1988. In 1992, L’Oreal started using a “modernized version” of the mark. Jean Alexander Cosmetics (Jean Alexander) (plaintiff) began using its “EQ System” mark in 1990; it registered the mark with the United States Patent and Trademark Office (PTO) in 1993. In 1996, L’Oreal attempted to register its modernized mark. The examiner rejected L’Oreal’s application based on a likelihood of confusion with the EQ System mark. L’Oreal petitioned the Trademark Trial and Appeal Board (TTAB) to cancel Jean Alexander’s mark, arguing that L’Oreal’s modernized mark was legally equivalent to the 1988 version and therefore had priority over Jean Alexander’s mark. Both parties litigated the matter extensively. Ultimately, the TTAB denied L’Oreal’s petition because its modernized mark was not equivalent to the original and, consequently, did not have priority. The TTAB also held, “solely for the sake of completeness,” that there was no likelihood of confusion between L’Oreal’s modernized mark and Jean Alexander’s mark. L’Oreal applied to register its modernized mark, which Jean Alexander opposed. The PTO registered the mark, and the TTAB ruled that issue preclusion prevented Jean Alexander’s opposition. Jean Alexander sued L’Oreal in federal court for trademark infringement. The court dismissed the suit based on issue preclusion. Jean Alexander appealed.