Trademark dilution law provides mark owners with another federal claim against unauthorized users in addition to the traditional claim for infringement. While dilution law has become a major vehicle of trademark enforcement for many branding companies, its rationale has been criticized by scholars, particularly, in terms of the ambiguous concept of the harm allegedly cause by dilution. Given the issue, this study examined whether dilutive use of famous sport trademarks has substantially harmful effects on the distinctive psychological value of the senior marks. It first attempted to develop an ad hoc measurement solution based on Keller’s (1993) brand equity theory. A follow-up quasi-experimental study examined the impact of given dilutive information. The result shows that a majority of the senior marks revealed substantially increased brand equity scores rather than decreased value. The result suggests that the harm argued in light of dilution theory is questionable, which calls for more empirical proofs.
