Almost anything can function as a trademark. But in order to acquire federal protection, matter must not only be used in commerce; it must be used as a mark—featured in a way that will draw consumers’ attention to it and lead them to view it as a source indicator. In assessing trademark protectability, the USPTO and federal courts consistently emphasize distinctiveness over use as a mark: they focus on what the mark is, rather than what the mark does. Distinctiveness has received the lion’s share of attention, generating rules and tests applied in thousands of cases and discussed in hundreds of articles, books, and practice guides. At the same time, courts have struggled to articulate and apply a clear standard for use as a mark separate from distinctiveness. Both are necessary for trademark protection because each plays a role in determining whether consumers will perceive matter as a mark. Yet, somehow use as a mark became the red-headed stepchild of trademark law, and distinctiveness got all the glory. While the Lanham Act requires use as a mark for protection, and empirical studies reflect its importance, courts and the USPTO have been reluctant to assign it greater weight in assessing trademark protectability, validity, and priority. This Article explores how factfinders have considered (or failed to consider) use as a mark in both ex parte and adversarial contexts and argues that merging distinctiveness and use as a mark analyses would lead to more accurate outcomes. Ultimately, the relationship between use as a mark and distinctiveness is interdependent and inverse: the less distinctive a mark is, the more indicators of trademark use are needed to ensure consumers will perceive it as a mark, and vice-versa. Matter that functions primarily as something else—decoration, domain name, serial number, hashtag—also requires more traditional trademark use to ensure it is perceived as a trademark. Integrating use as a mark with distinctiveness assessments would reinvigorate both doctrines and help ensure that statutory and common law requirements are met and chilling effects avoided by protecting only matter that consumers actually perceive as a source indicator. When it neglects consumer perception, ostensibly its core concern, trademark law itself fails to function.
