The 13 DuPont Factors: Trademark Likelihood of Confusion Test

The DuPont factors are the 13 considerations the U.S. Patent and Trademark Office and federal courts use to decide whether a new trademark is likely to be confused with an existing one. They come from the 1973 decision In re E. I. du Pont de Nemours & Co., where the Court of Customs and Patent Appeals set out a structured framework for evaluating whether two marks are too similar to coexist on the federal register.¹ That framework now governs every federal trademark application and shapes most infringement disputes, making it the central analytical tool in U.S. trademark law.

The underlying rule sits in Section 2(d) of the Lanham Act, 15 U.S.C. § 1052(d), which bars registration of any mark likely to cause confusion, mistake, or deception when used in connection with the applicant’s goods.² Nobody has to prove that a real consumer was actually confused. The question is whether a reasonable probability of confusion exists based on the overall commercial impression the marks create, and the DuPont decision gave that question a structure.³

The 13 DuPont Factors

The court identified these 13 factors, while cautioning that no single formula resolves every case. Not all of them matter in every dispute; only the factors supported by evidence in the record need to be considered.³

Factor 1 — Similarity of the marks: How alike the marks are in appearance, sound, meaning, and overall commercial impression.
Factor 2 — Relatedness of goods or services: Whether the products or services are similar enough that consumers might assume they come from the same source.
Factor 3 — Trade channels: Whether the goods or services move through the same distribution networks or retail environments.
Factor 4 — Purchasing conditions: Whether buyers make careful, researched decisions or quick impulse purchases.
Factor 5 — Fame of the prior mark: How widely recognized the existing mark is among consumers.
Factor 6 — Third-party marks: The number and nature of similar marks already in use on similar goods.
Factor 7 — Actual confusion: Whether real-world instances of confusion have been documented.
Factor 8 — Length of concurrent use: How long both marks have coexisted without evidence of confusion.
Factor 9 — Variety of goods: The range of products on which a mark is or is not used.
Factor 10 — Market interface: The relationship between the applicant and the prior mark owner in the marketplace.
Factor 11 — Right to exclude: The extent to which the applicant can prevent others from using its mark.
Factor 12 — Extent of potential confusion: How widespread the confusion could become if registration is granted.
Factor 13 — Catch-all: Any other established fact relevant to the effect of use.

Factor 13 is deliberately open-ended. It lets examiners and judges account for circumstances the first twelve don’t neatly capture, which is one reason the framework has held up for more than fifty years.

The Two Factors That Usually Decide the Case

Although all 13 can come into play, the Trademark Manual of Examining Procedure identifies two as the key considerations in any likelihood of confusion analysis: the similarity of the marks and the relatedness of the goods or services.³ When two marks look or sound alike and cover similar products, that combination alone usually supports a refusal. Neutral findings on the remaining factors rarely overcome a strong showing on these two.

Similarity of the Marks

Examiners compare marks in their entireties rather than pulling apart individual words or design elements. The Federal Circuit has said that while you can give more or less weight to a particular feature for rational reasons, the final conclusion must rest on the marks as whole units.⁴ The comparison looks at four dimensions: visual appearance, sound when spoken, meaning or connotation, and the overall commercial impression a consumer takes away.

Marks do not have to be identical to trigger a refusal. One that sounds the same but is spelled differently, or one that conveys the same idea through different words, can still create confusion. The test is whether the overall impression is similar enough to mislead a reasonable consumer about the source of the product.

Relatedness of Goods or Services

The goods or services don’t need to be identical either. They just need to be related enough that a consumer seeing similar marks on each would reasonably assume the same company produced both. A trademark for athletic shoes and a trademark for athletic socks cover different products, but they overlap so heavily in the consumer’s mind that similar marks on each would likely cause confusion.

The examining attorney considers what the goods are, who buys them, and how they are marketed. The question is not whether the goods themselves are confusable, but whether the marks used on them would confuse consumers about who stands behind the products.³

Why Fame Amplifies Everything Else

Fame is sometimes called a dominant factor because a well-known mark gets a broader zone of protection. When a mark has achieved widespread consumer recognition, confusion can be found even where the marks are less similar or the goods less closely related than would normally trigger a refusal. A less famous mark receives a narrower scope of protection, so the newcomer’s mark and goods have to be much closer before confusion becomes likely.

Fame in this context is evaluated on a spectrum. Examiners and the Trademark Trial and Appeal Board look at sales volume, advertising spending, how long the mark has been used, market share, and consumer recognition studies. A mark does not need to be a household name to qualify as famous in this analysis; it needs to be widely recognized among the relevant purchasing public.

How Mark Strength Fits In

Closely related to fame is inherent distinctiveness, which affects how much protection a mark receives from the start. The USPTO places marks on a spectrum from strongest to weakest:⁵

Fanciful: Invented words with no meaning outside the brand, like EXXON for petroleum. Easiest to protect.
Arbitrary: Real words used for unrelated goods, like APPLE for computers.
Suggestive: Words that hint at a quality without describing it, like COPPERTONE for sun-tanning products.
Descriptive: Words that directly describe the goods, like “Creamy” for yogurt. Not registrable on the principal register unless they have acquired distinctiveness through long, extensive commercial use.
Generic: The common name for the product itself, like “Bicycle” for bicycles. Cannot function as trademarks.

Where a mark sits on this spectrum matters for confusion analysis. A fanciful or arbitrary mark gets the broadest protection, so even somewhat distant marks on loosely related goods might trigger a refusal. A descriptive mark that barely cleared the distinctiveness threshold gets the narrowest.

When the Field Is Already Crowded

Factor 6 asks how many similar marks already exist on similar goods. If a particular word or element appears across numerous active registrations and actual marketplace use, that suggests the element is relatively weak and consumers have learned to look at other features to tell brands apart. A crowded field narrows the scope of protection for every mark in it.⁶

Not all third-party registrations carry the same weight. Registrations based on actual use in commerce are the most persuasive. Registrations filed through international treaties that have never been backed by a use-based affidavit carry very little weight, and expired or cancelled registrations are not useful evidence at all.⁶

Buyer Sophistication and Purchasing Conditions

How carefully consumers shop for your type of product affects the analysis directly. Expensive or specialized goods tend to be purchased with more research and deliberation, which reduces the chance that similar marks will mislead anyone. Cheap, everyday products are more likely to be grabbed on impulse, which increases the risk of confusion.

Sophistication is not a free pass. The TMEP is clear that even knowledgeable buyers in a specialized field can be confused by very similar marks. The analysis is calibrated to the least sophisticated potential purchaser in the relevant market, not the most careful one. And when a purchase is quick but the underlying decision is important, such as choosing a healthcare provider, the TTAB still treats it as a careful purchase.⁷

Actual Confusion Versus Long Coexistence

Evidence that consumers have actually been confused is powerful but uncommon. Misdirected emails, customer complaints sent to the wrong company, or survey data showing brand mix-ups can all serve as direct proof. When it exists, actual confusion evidence tends to push the analysis strongly toward a finding of likelihood of confusion.

The flip side is a long period of coexistence without any documented confusion. That can support an applicant’s case, but only if the record shows there was a meaningful opportunity for confusion to occur. If two marks have coexisted for years in the same geographic market with overlapping customers and no one has ever mixed them up, that says something. If the marks were used in different regions or sold through completely separate channels, the absence of confusion proves very little.

What to Build Your Evidence Around

Whether you are applying for a new mark or defending an existing one, the evidence you gather should connect to specific DuPont factors. Vague assertions that your brand is “different” will not persuade an examiner or the TTAB. The materials that tend to matter most include marketing collateral and website screenshots showing how the product is presented and sold, sales figures and advertising spend that establish the fame of a mark, consumer surveys demonstrating how the relevant public perceives the marks, misdirected customer communications that document actual confusion, and third-party registration searches showing the marketplace is already crowded.

Tie each piece of evidence to the factor it supports. Examiners and the TTAB evaluate the factors individually before weighing them together, so a disorganized evidence dump is easier to dismiss than a targeted one.

Responding to a Section 2(d) Refusal

When a trademark examining attorney concludes that your mark is likely to be confused with an existing registration, they issue an Office Action. You generally have three months from the date of the notice to respond, with the option to request a three-month extension by paying an additional fee.⁸ Missing the deadline, including any extension you have paid for, kills the application.

A response can take several approaches, and you can combine more than one:⁹

Argue the marks are different in appearance, sound, meaning, or commercial impression.
Argue the goods or services are unrelated, target different customers, or move through different trade channels.
Narrow your identification of goods or services to eliminate the overlap. Be cautious: you generally cannot broaden the identification back to its original scope later.
Obtain a consent agreement from the owner of the cited registration explaining why confusion is unlikely. A bare statement of consent is not enough; the agreement needs specific reasoning. The examiner will not grant extra time to negotiate one, so start early.
Check whether the cited registration has been cancelled or has expired. A dead registration can no longer serve as a bar.

Consent agreements deserve extra attention because applicants often overlook them. Even with a solid agreement the examiner keeps discretion to maintain the refusal, but in practice a well-drafted consent agreement resolves many Section 2(d) problems.

What Happens If the Examiner Isn’t Persuaded

If your response does not move the examiner, a final refusal follows. From there you can appeal to the Trademark Trial and Appeal Board. The electronic filing fee for an ex parte appeal is $225 per class of goods or services.¹⁰ The Board reviews the examining attorney’s decision to determine whether it was correctly made, and it can affirm the refusal on a different rationale than the one the examiner relied on.¹¹

If the TTAB affirms, you have two further options: appeal to the U.S. Court of Appeals for the Federal Circuit, or file a civil action in a federal district court. The Federal Circuit reviews the TTAB’s record. The district court route lets you introduce new evidence. Most applicants pick the Federal Circuit because it is faster and less expensive, but the district court option matters when the evidence you need was not in the administrative record.

Do the DuPont Factors Apply in Infringement Lawsuits?

The DuPont factors govern USPTO proceedings, but when trademark disputes end up in federal court as infringement lawsuits, different circuits use their own multi-factor tests. The Second Circuit uses the eight-factor Polaroid test.¹² The Ninth Circuit uses the eight-factor Sleekcraft test, and in domain name disputes gives extra weight to what it calls the “Internet Troika”: similarity of the marks, relatedness of the services, and simultaneous use of the internet as a marketing channel.¹³ The Third Circuit uses the ten-factor Lapp test.¹⁴

The core questions across all of these tests overlap heavily with DuPont, but the labels, the number of factors, and the emphasis vary enough to change the analysis. If you are evaluating or defending an infringement claim, the circuit’s own test controls, not DuPont directly.

What a Finding of Confusion Costs

In the USPTO context, a finding of likelihood of confusion means your application is refused and you do not get a federal registration. In litigation, the stakes are higher. Courts can order the infringing party to stop using the mark, and under 15 U.S.C. § 1116 a plaintiff who proves a violation is entitled to a rebuttable presumption of irreparable harm, which makes permanent injunctions easier to obtain than in many other areas of law.¹⁵

Under 15 U.S.C. § 1117, a prevailing plaintiff can also recover the defendant’s profits, the plaintiff’s actual damages, and the costs of the action. Counterfeit-mark cases carry statutory damages ranging from $1,000 to $200,000 per counterfeit mark per type of goods or services, and up to $2,000,000 per mark per type of goods or services if the counterfeiting was willful. The Lanham Act also lets courts award reasonable attorney fees to the prevailing party in “exceptional cases,” a provision that cuts both ways: a defendant who wins an exceptional case can recover fees from the plaintiff.¹⁶

1
TransJurLex. In re E.I. duPont de Nemours and Co., 476 F.2d 1357
2
Office of the Law Revision Counsel. 15 USC 1052 – Trademarks Registrable on Principal Register
3
BitLaw. Trademark Manual of Examining Procedure – 1207.01 Likelihood of Confusion
4
BitLaw. Trademark Manual of Examining Procedure – 1207.01(b) Similarity of the Marks
5
United States Patent and Trademark Office. Strong Trademarks
6
BitLaw. Trademark Manual of Examining Procedure – 1207.01(d)(iii) Third-Party Registrations
7
BitLaw. Trademark Manual of Examining Procedure – 1207.01(d)(vii) Sophisticated Purchasers
8
United States Patent and Trademark Office. Response Time Period
9
United States Patent and Trademark Office. Responding to Office Actions
10
United States Patent and Trademark Office. USPTO Fee Schedule
11
United States Patent and Trademark Office. Trademark Board Manual of Procedure – Chapter 1200 Ex Parte Appeals
12
Justia. Polaroid Corp. v. Polarad Electronics Corp., 287 F.2d 492
13
Ninth Circuit District and Bankruptcy Courts. Infringement – Likelihood of Confusion – Factors – Sleekcraft Test
14
United States Court of Appeals for the Third Circuit. Checkpoint Systems, Inc. v. Check Point Software Technologies, Inc.
15
Office of the Law Revision Counsel. 15 U.S. Code 1116 – Injunctive Relief
16
Office of the Law Revision Counsel. 15 U.S. Code 1117 – Recovery for Violation of Rights