The Principle of Burden of Proof in Trademark Cancellation Lawsuits Filed by Interested Third Parties

The principle of the allocation of the burden of proof in such lawsuits generates complex problems within the intellectual property (IP) evidentiary system, particularly due to the imbalance of legal standing between registered trademark owners and third parties filing cancellation claims on the grounds of non-use for three consecutive years. This study advances new arguments in: (1) the philosophical foundations of intellectual property/trademark law and the principle of equitable evidentiary rules, and (2) the ratio legis and the principle of burden-sharing in such third-party claims. The rigid application of the maxim actori incumbit probatio is no longer adequate in the context of modern commerce. Establishing proof of a negative fact—namely, the non-use of a trademark—requires a new paradigm in the form of a limited reverse burden of proof mechanism. The evidentiary burden may be proportionally shifted to the trademark owner, obliging them to demonstrate genuine use. The lack of clarity in the regulation of non-use evidence has resulted in disparities in judicial decisions and legal uncertainty. Accordingly, this study, employing a normative legal research method, concludes that a reconstruction of evidentiary principles that are fair and balanced is necessary.