Exploration of the "Use as a Trademark" Element in Trademark Infringement Determination: Focusing on the Actual Functional Impairment of the Trademark as the Core Criterion

In the theory and judicial practice of trademark law, the limitations of the formal requirement of "whether used as a trademark" in determining trademark infringement have become increasingly prominent. Based on the research background of UK trademark law, this study explores the paradigm shift in the core of trademark infringement determination from "formal use" to "substantial damage". By integrating the diversified functions of trademarks, the special protection rules for well-known trademarks, the logic behind assessing the likelihood of confusion, and the fundamental values of trademark law, the research highlights that the focus should be on whether the alleged act has caused substantial damage to the identifying function, goodwill value, or market competition order of the trademark. The findings reveal that it is more pertinent to assess the impact of the contested action on the trademark's essential functions rather than to impose a mechanical requirement for the actor to exhibit a subjective purpose or objective form of "use as a trademark". Such a shift not only accords with the essential requirements of trademark law to protect multiple functions and maintain market order but also achieves a balance between right protection and competition promotion in a dynamic business environment, providing a more adaptable legal framework for addressing new types of infringement.