Trademark Likelihood of Confusion and the Doctrine of Tacking: A Strategic Response to USPTO Refusals
When the USPTO refuses a trademark application based on “likelihood of confusion,” it’s often the most frustrating hurdle for applicants. The refusal can feel subjective, unpredictable, and difficult to overcome. But with the right strategy—especially in cases involving evolving brands—the doctrine of tacking can be a powerful, though narrowly applied, tool.
This post breaks down what “likelihood of confusion” really means, why refusals happen, and how tacking may help you push past them.
What Is “Likelihood of Confusion”?
A refusal based on “likelihood of confusion” is one of the most common and challenging barriers in U.S. trademark prosecution. At its core, trademark law is about preventing consumer confusion. The USPTO (and courts) ask a simple question: Would an ordinary consumer mistakenly believe that two marks come from the same source?
To answer that, the USPTO evaluates likelihood of confusion using a multi-factor analysis derived from In re E. I. du Pont de Nemours & Co. These factors include:
(1) the similarity of the marks in appearance, sound, meaning, and commercial impression;
(2) the relatedness of the goods or services;
(3) overlap in trade channels and classes of consumers;
(4) the strength or distinctiveness of the cited mark; and
(5) any evidence of actual confusion.
Although no single factor is dispositive, the similarity of the marks and the relatedness of the goods or services typically carry the greatest weight in the analysis.
Why Refusals Happen
Refusals generally arise where the applied-for mark closely resembles a prior registered mark, the goods or services are identical or sufficiently related, or the cited mark is strong or widely recognized. Even relatively small similarities—especially those affecting the dominant portion of a mark—may be sufficient to support a refusal. As a result, applicants often face difficulty overcoming refusals that may appear subjective or unpredictable.
Strategies to Overcome a Refusal
To address such refusals, applicants commonly employ several established strategies. One approach is to distinguish the marks by highlighting differences in their visual appearance, pronunciation, or overall commercial impression. Another is to amend the identification of goods or services to narrow the scope and eliminate overlap with the cited registration. Applicants may also challenge the strength of the cited mark by presenting evidence of third-party use, thereby suggesting that the mark is weak or diluted. In some cases, a consent agreement between the applicant and the registrant can be persuasive evidence that confusion is unlikely.
Enter Tacking: A More Advanced Strategy
In more complex situations, particularly where a brand has evolved over time, the doctrine of tacking may provide an alternative path. Trademark rights are generally tied to the first use of a mark in commerce. Tacking is a limited exception that allows a trademark owner to claim priority based on an earlier version of a mark, even if the current version has changed. This is only permitted where the two marks are considered “legal equivalents,” meaning they create the same continuing commercial impression such that consumers would perceive them as essentially the same mark.
Tacking becomes particularly relevant when an applicant has modified its mark over time and the USPTO cites a third-party mark that predates the current version but not the earlier version. If the applicant can successfully tack the newer mark onto the earlier one, it may establish priority over the cited registration and thereby overcome the refusal. In this way, tacking can serve as a decisive tool when priority is the central issue.
However, the doctrine is narrowly construed and subject to a high evidentiary bar. Courts and the USPTO require that the marks be virtually indistinguishable in their commercial impression. Minor stylistic or typographic updates, modernization of spelling, or the removal of descriptive or generic matter may qualify. By contrast, changes that alter the meaning, add or remove distinctive elements, or otherwise constitute substantive rebranding will generally defeat a tacking claim.
A successful tacking argument requires a careful and well-supported presentation. The applicant must establish priority by providing evidence of use of the earlier mark, such as dated specimens, advertising materials, or packaging. It must then demonstrate that the earlier and current marks are legal equivalents, emphasizing their shared commercial impression. Finally, the applicant must show continuous use of the mark over time, effectively connecting the earlier version to the present one without interruption.
Practical Tips
From a strategic perspective, tacking should be used with caution. Applicants should:
Document brand evolution: Keep records of logo changes, packaging, and marketing materials over time.
Be realistic: Tacking is a narrow doctrine—don’t rely on it if the marks are meaningfully different.
Use it strategically: It’s most effective when priority is the key issue in a refusal.
Moreover, weak or unsupported tacking arguments may undermine an applicant’s overall position.
Final Thoughts
Likelihood-of-confusion refusals remain a central feature of trademark examination, but they are not insurmountable. While traditional arguments often provide a viable path forward, the doctrine of tacking offers a more sophisticated alternative in cases involving incremental changes to a mark. Given its limited scope and demanding standard, tacking is best understood as a strategic, case-specific tool that, when properly supported, can preserve priority and enable registration where it might otherwise be denied.