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Likelihood of confusion, in plain English
Nearly every serious trademark question comes back to one test. Here is what "likelihood of confusion" means, how the USPTO applies it, and what happens when your application runs into it.
Written by Trademarky. Last checked September 4, 2026. 7 min read.
The question the USPTO asks
Section 2(d) of the Trademark Act says the USPTO must refuse a mark that so resembles a registered mark, or a mark in an earlier-filed application, that it is likely to cause confusion, mistake or deception when used on the applicant's goods or services. Two words in that sentence do the work. "Resembles" means the marks need not be identical. "Likely" means probable, not merely possible; a far-fetched confusion does not count.
The practical question is this: would an ordinary buyer of these goods, seeing the two marks in the marketplace, probably believe they come from the same company or from companies connected in some way? The same test decides infringement cases in court, with a similar list of factors.
The USPTO's list of factors comes from a 1973 court decision and is known as the du Pont factors; the USPTO's own page on likelihood of confusion gives the short version. Two factors decide most cases: how similar the marks are, and how related the goods and services are. The rest adjust the answer.
The marks: sound, appearance and meaning
Marks are compared as a whole, for the overall impression they leave, on three axes:
- Sound. Loopwell, Lupwell and Loop Well are the same word to a customer who hears a recommendation. Spelling changes that do not change the sound rarely change the result.
- Appearance. Acmeflow and ACME FLOW look alike. A mark registered in standard characters covers every font, size and color, so it is compared against every way the other mark might be written.
- Meaning. Two marks that translate into each other, or call the same idea to mind, can be similar even when they share no letters. Under the doctrine of foreign equivalents, a foreign word many U.S. buyers understand is translated before it is compared, so Northwind and a foreign phrase meaning north wind may be treated as the same mark.
Some parts of a mark weigh more than others. The dominant portion, often the first word or the coined word, carries the comparison. Descriptive or generic words, and anything the applicant has been asked to disclaim, count for little: adding "Bakery" to a name that conflicts with an existing Hazel & Rye does not separate the two.
The goods: how related is related
Marks are compared for the goods and services each one covers, never in the abstract. The goods do not have to be identical, competitive or even in the same class; classes are an administrative filing system, and the examining attorney looks past them. The question is whether buyers who encounter the two marks would expect the goods to come from a single source or from related ones.
Goods are related when they are the kind that one company commonly sells together, when one is used with the other, or when they are sold to the same customers in the same places for the same purpose. Coffee and baked goods, jackets and boots, software and the support services for it: each pair is related often enough that a similar name across them is a real risk. Evidence comes from third-party registrations that list both goods under one mark and from websites that sell both.
The two big factors trade off against each other. Where the marks are nearly identical, the goods need only be loosely related for a refusal to follow. Where the goods are identical, marks with less in common can conflict. That trade-off is why a search that only asks "is the exact name taken in my class?" misses most of the risk; how to search for a trademark shows how to search the way the examining attorney thinks.
Trade channels, buyers and the other factors
The remaining factors adjust the weight of the first two. In the USPTO's own examination, several of them cut in a predictable direction:
| Factor | What it asks | What usually happens |
|---|---|---|
| Trade channels and buyers | Are the goods sold in the same places to the same people? | When neither registration limits its goods, the USPTO presumes the channels and buyers are the same |
| Conditions of purchase | Are buyers careful or impulsive? | Cheap, everyday goods are bought on impulse, which raises the risk; expensive goods bought by experts lower it, but rarely enough on their own |
| Fame of the earlier mark | How well known is the registered mark? | A famous mark gets a wide berth, and the USPTO treats fame as a heavy factor when there is evidence of it |
| Similar marks in use | How many similar marks coexist for these goods? | A crowded field makes the shared element weak and each mark's scope narrow |
No single factor is decisive. In a response, the applicant's job is to bring evidence on the factors that favor coexistence and to show why the two decisive factors come out differently than the office action assumes.
What a 2(d) refusal looks like
A likelihood of confusion refusal arrives as an office action. It names the cited registration or registrations by number, attaches copies of them, and walks through the factors: the marks are similar because of this word, the goods are related because of this evidence, the channels are presumed the same. The deadline is three months from the issue date, extendable once by three months for a USPTO fee.
If the conflicting mark is in an earlier-filed application that has not yet registered, you will see a different letter: a notice that your application is suspended until the earlier one registers or dies. What each USPTO trademark status means explains suspension and the other statuses.
The usual ways to answer
- Argue the marks apart. Show that the shared element is weak, that the marks differ in their dominant parts, or that the overall impressions differ in sound, look and meaning. Dictionary evidence and third-party registrations sharing the same word are the usual exhibits.
- Argue the goods apart. Show that the goods are sold in different channels to different buyers, or narrow your description of goods so that it no longer overlaps. Goods can be narrowed at any time, never broadened.
- Obtain a consent agreement. If the owner of the cited mark agrees that confusion is unlikely and the agreement explains why, with commitments about how each side will use its mark, the USPTO gives it great weight. The owner may want something in return.
- Challenge the cited registration. If the cited mark is no longer in use, a petition to cancel for abandonment, or an expungement or reexamination proceeding, can remove it.
- Change the mark. When the conflict is strong, a different name is often the cheapest answer, and cheaper before the filing fee than after.
A serious 2(d) response is legal writing with exhibits, and it is the kind of office action Trademarky quotes before any work begins, so that you can weigh the cost against the strength of the argument. The point of the comprehensive search your attorney reviews before filing is to find these conflicts first, while changing course still costs nothing.
The check runs the sound, look and meaning comparison against U.S. records first, and shows you the closest live marks. Check my trademark for free
Questions about this topic
Does changing the spelling of a name avoid likelihood of confusion?
Usually not. The USPTO compares marks by sound and meaning as well as appearance, and a spelling change that leaves the pronunciation intact leaves the conflict intact: Loopwell and Lupwell, or Northwind and Northwynd, are treated as the same word. A new spelling helps only when it changes how the mark sounds and what it brings to mind.
What is a consent agreement in a trademark application?
A written agreement in which the owner of the cited registration consents to your registration and explains why confusion is unlikely: differences in the goods, the customers or the channels, and steps each side will take to keep them apart. The USPTO gives a detailed agreement great weight. A bare statement of consent with no reasons carries much less.
Does likelihood of confusion apply to unregistered marks too?
In court, yes. An unregistered mark with common-law rights can be infringed, and the same kind of factors decide the case. At the USPTO, the examining attorney cites only registered marks and earlier-filed applications, so an unregistered business will not appear in an office action, but it can oppose your application after publication or petition to cancel your registration later.
Related guides
- Trademark office actions: what they are and how to respond: What a USPTO office action is, the three-month response deadline, the most common refusals, how a response is prepared, and what happens if you miss it.
- How to search for a trademark, and what a search misses: How to search USPTO trademark records yourself, how the USPTO compares marks, what a records search misses, and when to get an attorney's read.
- Someone is using my trademark: what you can do: Real conflict or look-alike, what a registration changes, cease-and-desist letters, USPTO protests and oppositions, and when to call the attorney.
This guide is general information to help you understand the process. It is not legal advice and does not create an attorney-client relationship. For advice on your own mark, talk to an attorney on a free call.
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This free check is an AI-assisted preliminary screening against known U.S. trademark records. It is not a comprehensive clearance search and not legal advice. Only a licensed attorney can advise you on whether to file.