Likelihood of Confusion
The legal standard the USPTO uses to evaluate whether two marks are too similar — and the framework for understanding your search results.
What Is Likelihood of Confusion?
Likelihood of confusion asks whether consumers would be likely to confuse the source of goods or services based on the similarity of two marks. This standard does not require actual confusion, identical marks, or identical goods. The question is whether confusion is probable given the totality of the circumstances.
The DuPont Factors
The framework for evaluating likelihood of confusion was established in In re E.I. du Pont de Nemours & Co. (1973). The court identified 13 factors, but two dominate most cases.
1. Similarity of the Marks
Marks are compared in their entireties across three dimensions: sight (visual appearance), sound (pronunciation), and meaning (conceptual content). Marks similar in any one dimension may create confusion. "TIDE" and "TYDE" sound identical. "SUN COAST" and "BEACH SHORE" convey a similar meaning.
2. Relatedness of the Goods or Services
Goods do not need to be identical or competitive. They are "related" if consumers would reasonably expect them to come from the same source. Clothing and handbags are often related. Software and consulting services may be related if the consulting concerns the software.
Other Factors
Additional factors include the strength of the prior mark, purchase conditions, evidence of actual confusion, similarity of trade channels, and coexistence without confusion. These typically play a supporting role.
How This Affects Your Search
Understanding likelihood of confusion is essential for interpreting results. The question is not whether any similar mark exists — it almost certainly does — but whether any existing mark is similar enough, for related enough goods, to create a probability of consumer confusion.