Trademark Infringement and Likelihood of Confusion

By Hank FasthoffJuly 7, 2026

Trademark infringement occurs when someone uses a mark in commerce in a way that's likely to confuse consumers about the source, sponsorship, approval, or affiliation of goods or services. The dispute concerns the commercial impression created by the challenged use, with isolated similarities supplying only part of the evidence.

Section 32 of the Lanham Act governs infringement of a federally registered mark. Section 43(a) protects qualifying unregistered marks and trade dress through a false designation of origin claim. Under either provision, the owner must establish enforceable trademark rights and a likelihood that the defendant's unauthorized domestic use in commerce will cause confusion, mistake, or deception.

Trademark Rights and Priority

Trademark rights based on use arise when a mark identifies the source of goods or services. Priority of use establishes ownership subject to statutory priority rules, and an unregistered owner must prove when, where, and for what goods or services it established rights. Sales records, advertising, archived webpages, packaging, invoices, customer testimony, and licensing records establish that history.

Federal registration changes the proof and the geographic consequences. Under Sections 1057(b) and 1115(a), a registration on the principal register is prima facie evidence of validity, ownership, and the exclusive right to use the mark for the goods or services identified in the registration, subject to its conditions and limitations. If the right to use becomes incontestable under Section 1065, Section 1115(b) makes that evidence conclusive, subject to the defenses and defects listed in the statute.

A qualifying earlier user retains superior rights despite a subsequent registration. Section 1057(c) provides nationwide constructive priority from the application filing date once the mark registers, but it preserves the rights of a qualifying prior user. Section 1115(b)(5) limits that prior user defense to the geographic area in which continuous prior use is proved.

Federal Courts Use Different Factor Tests

No single national list governs every likelihood of confusion case. Federal appellate courts use related factor tests that organize the evidence without converting the inquiry into a scorecard.

The Fifth Circuit uses eight digits of confusion. They examine the type of mark, mark similarity, product or service similarity, retail outlets and purchasers, advertising media, intent, actual confusion, and purchaser care. The court applied those digits in Springboards to Education, Inc. v. Houston Independent School District, 912 F.3d 805, 812 (5th Cir. 2019).

The Second Circuit applies the factors from Polaroid Corp. v. Polarad Electronics Corp., 287 F.2d 492 (2d Cir. 1961), which include product proximity, whether the senior user is likely to enter the junior user's market, product quality, and purchaser sophistication. The Ninth Circuit uses the factors from AMF Inc. v. Sleekcraft Boats, 599 F.2d 341 (9th Cir. 1979), which include marketing channels and likely market expansion. Names and formulations differ, but every circuit examines the marks as consumers encounter them, the relationship between the parties' offerings, and the circumstances under which purchasers make their decisions.

A court weighs the factors according to the record before it. One factor can assume unusual importance, and a plaintiff doesn't have to win a majority of them. Before applying any list, the parties must identify the relevant consumers and the market in which those consumers encounter the marks. In Springboards to Education, Inc. v. Mission Independent School District, No. 21-40337 (5th Cir. Apr. 26, 2023), the Fifth Circuit declined to parse the digits because the claimant identified the wrong consumers and presented evidence directed to a different group.

Strength of the Asserted Mark

Strength has conceptual and commercial components. Conceptual strength concerns where the mark falls on the spectrum from generic through descriptive, suggestive, arbitrary, and fanciful. Generic terms can't function as trademarks for the goods or services they name, while descriptive terms require acquired distinctiveness before they receive protection.

Commercial strength concerns marketplace recognition. Advertising expenditures, sales, duration and geographic extent of use, unsolicited media coverage, survey evidence, licensing, and consumer testimony show whether buyers associate the mark with one source. Courts narrow the scope of protection when substantial third party use teaches consumers to distinguish among marks that share the same term or feature.

Similarity in Marketplace Context

Courts compare appearance, sound, meaning, and overall commercial impression. They consider the complete marks as consumers encounter them rather than dissecting each mark into separate words, colors, or design features. House marks, packaging, disclaimers, webpage layout, and surrounding text affect the comparison according to their prominence, though a defendant can't always cure a confusing use by adding its company name.

The manner of purchase also affects similarity. Consumers scrolling search results, hearing a mark spoken, or making a quick retail purchase encounter marks differently from procurement officers comparing written proposals. Evidence should reproduce the marketplace encounter instead of presenting only enlarged logos side by side.

Goods, Services, Channels, and Purchasers

Competing products support confusion, but direct competition isn't required. Confusion includes a mistaken belief that one company sponsored, licensed, approved, or expanded into another company's related offering. Courts therefore examine the relationship between the goods or services, not merely the industry labels assigned to them.

Sales channels and advertising show where consumers encounter both parties. Shared websites, retailers, trade shows, social platforms, search terms, geographic markets, and referral sources support confusion when they expose the same consumers to both marks. Separate channels and distinct customer groups point the other way.

Purchaser care depends on price, frequency, urgency, sophistication, and the conditions of sale. A high price supports careful purchasing in some markets, but institutional buyers can also rely on shorthand, referrals, or assumptions about affiliation. The evidence must address the actual purchaser rather than an abstract label such as consumer or professional.

Intent and Actual Confusion

Intent isn't an element of ordinary trademark infringement. Evidence that a defendant selected a mark to benefit from the owner's reputation supports an inference of likely confusion, while knowledge of the earlier mark by itself proves only awareness. Search reports, naming presentations, internal messages, copying of packaging, search advertising, and reactions to a demand letter reveal why the defendant adopted or continued using the mark.

Actual confusion provides strong evidence, but a plaintiff doesn't have to prove that a completed mistaken purchase occurred. Misdirected calls and emails, mistaken reviews, requests for support, distributor inquiries, and testimony qualify when they show confusion about source or sponsorship. Courts examine who was confused, what caused the confusion, and whether it concerned source or sponsorship instead of ordinary inattentiveness.

Consumer surveys measure likely confusion, secondary meaning, or other disputed perceptions. Survey design, the relevant population, controls, stimuli, questioning, and coding determine whether the results deserve weight. A poorly matched universe or a leading question reduces an expensive survey to weak evidence.

Reverse Confusion

Reverse confusion occurs when a commercially powerful junior user saturates the market with a mark that's the same as or similar to a smaller senior user's mark. Consumers then assume that the senior user is affiliated with, sponsored by, or derived from the junior user. The injury includes loss of identity, control, and the ability to expand under the senior user's mark.

Courts adapt the ordinary factors to that theory. They assess commercial strength through the junior user's market power and intent through whether the junior user conducted an adequate search and proceeded after learning of the senior user's rights. A complaint and expert analysis should identify reverse confusion directly because some evidence has a different significance under that theory.

Descriptive, Nominative, and Expressive Uses

Section 1115(b)(4) protects a good faith use of descriptive language otherwise than as a mark. In KP Permanent Make-Up, Inc. v. Lasting Impression I, Inc., 543 U.S. 111 (2004), the Supreme Court held that a defendant asserting classic fair use doesn't bear the burden of negating likely confusion. Some degree of confusion can coexist with the defense because the plaintiff retains the burden on infringement.

Nominative use identifies the trademark owner's goods or services when reference to the mark is necessary, such as resale, repair, comparison, commentary, or compatibility. Federal circuits analyze nominative use through different tests, so the governing circuit affects whether it functions as a defense or as part of the confusion analysis. The amount used and the presentation should avoid suggesting sponsorship.

Parody and expression don't receive automatic immunity. Jack Daniel's Properties, Inc. v. VIP Products LLC, 599 U.S. 140 (2023), held that the special threshold test for expressive works doesn't apply when the defendant uses the challenged designation as a mark for its goods. A humorous message influences the ordinary likelihood of confusion analysis when the evidence supports that reading, but source identifying use requires that analysis.

Other defenses include abandonment, functionality, prior use, license, first sale, laches, estoppel, and acquiescence. Their availability depends on the claim and facts. Resale protection for genuine goods also narrows when the goods are materially different, altered, repackaged, or sold without quality controls that form part of the trademark owner's goodwill.

Domestic Use After Abitron

The Lanham Act doesn't provide a worldwide remedy for every injury suffered by a United States trademark owner. Abitron Austria GmbH v. Hetronic International, Inc., 600 U.S. 412 (2023), held that Sections 1114(1)(a) and 1125(a)(1) apply only when the challenged use in commerce is domestic.

Global sales, foreign affiliates, online transactions, and imported goods require a transaction level record. You should identify where the mark was placed on goods, where offers and sales occurred, where advertising appeared, where title passed, and where customers received the goods. Domestic consumer confusion alone doesn't replace the domestic use required by Abitron.

Counterfeiting

Section 1127 defines a counterfeit as a spurious mark that's identical to, or substantially indistinguishable from, a registered mark. Civil counterfeiting remedies depend on a principal register registration that covers the goods or services at issue and is in use.

Knowledge and intent affect the remedy rather than the basic definition. Section 1117(b) requires three times the greater of profits or damages and a reasonable attorney fee, absent extenuating circumstances, when a defendant intentionally uses a mark while knowing it's counterfeit in connection with the sale, offering for sale, or distribution of goods or services. Section 1117(c) permits a plaintiff to elect statutory damages before final judgment, from $1,000 to $200,000 per counterfeit mark per type of goods or services, with a ceiling of $2 million for willful use.

To obtain an ex parte seizure order under Section 1116(d), an applicant must establish specific statutory findings and provide security. Section 1118 permits a court to order delivery and destruction of infringing labels, packaging, advertising, and tools used to make them. Neither remedy follows automatically from using a confusingly similar mark.

Injunctions and Monetary Relief

Section 1116(a) authorizes injunctions according to equitable principles. A plaintiff receives a rebuttable presumption of irreparable harm after proving a violation for a permanent injunction, or after showing likely success on the merits for preliminary relief or a temporary restraining order. The court then applies the remaining equitable requirements and sets the scope of relief.

Section 1117(a) provides for the defendant's profits, the plaintiff's damages, and costs, subject to Sections 1111 and 1114 and equitable principles. For profits, the plaintiff proves the defendant's sales, and the defendant proves costs and deductions. Actual damages require evidence connecting the infringement to lost sales, price erosion, corrective advertising, reputational injury, or another compensable loss.

Romag Fasteners, Inc. v. Fossil Group, Inc., 590 U.S. 212 (2020), held that willfulness isn't a prerequisite to a profits award under Section 1125(a), though the defendant's mental state remains important to the equitable remedy. Section 1117(a) permits a court to increase actual damages up to three times the amount assessed. It separately permits adjustment of an inadequate or excessive profits recovery to a just amount, and each adjustment must compensate rather than punish.

Dewberry Group, Inc. v. Dewberry Engineers Inc., 604 U.S. 321 (2025), held that the statutory phrase "defendant's profits" means the profits of the named defendant. A court can't combine a defendant's profits with those of legally separate affiliates merely because the entities operate as one commercial unit. The Supreme Court left other theories open, including the statute's just sum provision, proof of the defendant's true financial gain, and veil piercing.

Section 1117(a) authorizes reasonable attorney fees to the prevailing party in exceptional cases. Courts determine exceptionality under a totality of the circumstances analysis drawn from Octane Fitness, LLC v. ICON Health & Fitness, Inc., 572 U.S. 545 (2014), and examine the strength of the litigating position and the manner in which the parties conducted the case.

Registration notice affects monetary recovery. Under Section 1111, a registrant who doesn't display a statutory notice, including the ® symbol, can't recover profits or damages unless the defendant received actual notice of the registration. That limitation doesn't eliminate the infringement claim or the ability to seek appropriate injunctive relief.

Building the Record

If you're enforcing a mark, you should collect priority evidence, registration records, advertising, sales channels, customer communications, confusion evidence, and examples showing the challenged use in context. You should preserve webpages, marketplace listings, social posts, search results, packaging, and dated purchases before the defendant changes them.

If you've received a demand, you should examine priority, the registration's goods and services, marketplace use, consumer overlap, third party uses, defenses, and the claimant's delay. You should also preserve the naming process and trademark search because deleting those records creates a separate litigation problem.

Likelihood of confusion is a fact intensive inquiry governed by circuit precedent, but the central question is concrete. The case turns on what the relevant consumers are likely to believe when they encounter the challenged mark in the marketplace.