Likelihood of Confusion in Trademark Law

Likelihood of confusion is the most common reason trademark applications are refused by the United States Patent and Trademark Office. Under Section 2(d) of the Lanham Act, the USPTO will refuse registration of a mark that is likely to cause confusion with an existing registered mark or a mark in a prior-filed pending application. Understanding what constitutes likelihood of confusion — and how the USPTO evaluates it — is critical for anyone considering a trademark application.

What "Likelihood of Confusion" Actually Means

Likelihood of confusion does not require that two marks be identical. It exists when a reasonably prudent consumer would be likely to believe that the goods or services offered under one mark come from the same source as, or are associated with, the goods or services offered under another mark. The standard is not whether confusion is certain or even probable — it is whether confusion is likely. This is a lower threshold than many applicants expect, and it captures marks that are similar but not identical, covering related but not identical goods or services.

The DuPont Factors

The Trademark Trial and Appeal Board (TTAB) and federal courts evaluate likelihood of confusion using a multi-factor test derived from the landmark case In re E.I. du Pont de Nemours & Co. (1973). While thirteen factors were identified in that case, the two most critical are the similarity of the marks and the relatedness of the goods or services. The factors include the similarity of the marks in appearance, sound, connotation, and commercial impression; the similarity or relatedness of the goods or services; the similarity of the trade channels and classes of consumers; the conditions under which sales are made (impulse vs. careful purchasing); the fame of the prior mark; the number and nature of similar marks in use on similar goods; the nature and extent of any actual confusion; the length of time of concurrent use without actual confusion; the variety of goods on which the mark is used; the market interface between the applicant and the owner of the prior mark; the extent to which the applicant has a right to exclude others; and the extent of potential confusion.

Similarity of the Marks

The examining attorney compares the marks in their entireties for similarities in appearance, sound, connotation, and overall commercial impression. Marks do not need to be identical to be confusingly similar. Even marks that look different on paper can sound alike when spoken aloud (phonetic equivalents like "Luv" and "Love"), or create the same mental impression (semantic equivalents like "Tornado" and "Cyclone"). The test is not side-by-side comparison under a microscope — it is whether a consumer encountering the marks separately, at different times, would be confused about the source. Shared dominant elements weigh heavily, while differences in minor elements like generic or descriptive terms may not be sufficient to avoid confusion.

Relatedness of Goods and Services

The goods and services do not need to be identical for a likelihood of confusion finding. They need only be related in a way that consumers would likely assume they come from the same source. A mark for restaurant services and a mark for packaged food products may be considered related because consumers often associate both with the same company. The USPTO looks at whether the goods and services are complementary, whether they are sold through the same trade channels, whether they appeal to the same consumers, and whether there is evidence that companies commonly provide both types of goods or services under the same mark.

How to Reduce Your Risk of a §2(d) Refusal

The single most effective way to avoid a likelihood of confusion refusal is to conduct a comprehensive clearance search before filing your application. A proper search examines not just identical marks but phonetic equivalents, translations, synonyms, and marks with similar commercial impressions across all relevant classes of goods and services. Beyond the search, choosing a highly distinctive mark — fanciful or arbitrary rather than descriptive or suggestive — reduces the likelihood of overlap with existing registrations. If a potential conflict is identified, an experienced trademark attorney can evaluate the strength of the argument for or against confusion and advise on whether to proceed, modify the mark, or pursue a different mark entirely. For more on choosing a distinctive mark, see our guide to choosing a strong trademark.

Responding to a §2(d) Office Action

If the USPTO issues a Section 2(d) office action refusing your application based on likelihood of confusion, you have three months to respond (extendable to six months with an extension request). A successful response requires a legal argument demonstrating that confusion is not likely, typically by distinguishing the marks, distinguishing the goods and services, or both. Arguments may include evidence that the marks create different commercial impressions, that the goods and services travel through different trade channels, that consumers exercise a high degree of care in purchasing, or that third-party registrations demonstrate that similar marks coexist for similar goods. The strength and specificity of these arguments determine whether the refusal is overcome. Our office action response services are specifically designed to handle these situations.