Defenses to a Trademark Infringement Claim

Last updated: November 2026

The main defenses to a trademark infringement claim are no likelihood of confusion, a plaintiff's mark that is weak, generic, or abandoned, prior use by the defendant, descriptive or nominative fair use, and laches. The Lanham Act lists several of these as defenses even against an incontestable registration. (15 U.S.C. § 1115(b).) Kolmogorov Law, P.C. defends Orange County, Los Angeles, and other California businesses accused of infringement, and plans around these defenses when it sues.

Call (909) 235-6116 or contact us online if your business has been accused of trademark infringement.

Trademark infringement defenses start with the plaintiff's burden

The first defense is not a defense at all. The plaintiff has to prove that confusion is likely. Often it cannot. The marks differ in sound or meaning. The goods are unrelated. The customers are sophisticated buyers who read labels, or the parties sell through different channels. Our page on proving infringement walks through the eight factors; a defendant works the same list from the other direction.

A registration does not change that burden. It is prima facie evidence of validity and ownership, nothing more. The statute expressly preserves every legal and equitable defense the defendant could have raised against an unregistered mark. (15 U.S.C. § 1115(a).) Even an incontestable registration remains subject to proof of infringement. (15 U.S.C. § 1115(b).)

Attacking the mark itself

A generic term, the common name for the product, is not a mark. A descriptive term without secondary meaning is not protectable either. A design feature that is functional cannot be a trademark. And a mark whose use has been discontinued with no intent to resume is abandoned. Three consecutive years of nonuse is prima facie evidence of that. (15 U.S.C. § 1127.)

These attacks can go beyond the lawsuit. A registration can be cancelled at any time if the mark has become generic, is functional, has been abandoned, or was obtained by fraud. (15 U.S.C. § 1064(3).) A court hearing an infringement case can order cancellation itself. (15 U.S.C. § 1119.) A defendant with a real cancellation argument should plead it as a counterclaim. Our page on TTAB proceedings versus litigation covers when to use which forum.

Prior use

Trademark rights come from use, so the business that used the name first usually wins, registration or not. The Lanham Act preserves the senior user's position against a later registrant. A party that adopted the mark without knowledge of the registrant's use, and has used it continuously since before the registrant's filing date, keeps the right to use it. The catch is territory: the defense applies only in the area where that continuous use is proved. (15 U.S.C. § 1115(b)(5).) In practice this defense ends many small-business cases. A decade of local use beats a two-year-old certificate, within the territory the evidence covers. Our page on unregistered trademark rights explains how that territory is proved.

Descriptive fair use of a trademark

A defendant may use a term descriptively, in good faith, to describe its own goods or their geographic origin. That is so even if someone else has registered the same term as a mark. (15 U.S.C. § 1115(b)(4).) The question is whether the defendant is using the words as words or as a brand. "Fresh baked daily" on a bakery window is descriptive. "Fresh Baked Daily" as the bakery's name is not. The defense also covers an individual's use of his or her own name, other than as a mark.

Nominative fair use

Sometimes the only way to describe what you sell is to name someone else's mark: a shop that repairs a particular brand of car, a reseller of genuine goods, a comparison ad. The Ninth Circuit treats this as nominative fair use when three conditions are met. The product or service is not readily identifiable without the mark. The defendant uses only as much of the mark as is reasonably necessary. And the defendant does nothing that, together with the mark, suggests sponsorship or endorsement. (New Kids on the Block v. News America Publishing, Inc. (9th Cir. 1992) 971 F.2d 302, 308.) Using the plaintiff's logo rather than its name usually fails the second and third conditions. The same analysis governs many keyword advertising disputes.

Laches, acquiescence, and estoppel

The Lanham Act has no limitations period. Delay is judged under equitable principles, which the statute lists as a defense: laches, estoppel, and acquiescence. (15 U.S.C. § 1115(b)(9).) Laches requires an unreasonable delay after the plaintiff knew or should have known of the use, plus prejudice to the defendant, such as years of investment in the name. Courts in California use the most analogous state limitations period as a benchmark. A plaintiff who sues within it is presumed diligent. One who sues after it has to explain the wait. Acquiescence means the plaintiff implied consent. Both defenses can limit damages even where they do not bar an injunction against a deliberate infringer.

What we do

We start by testing the mark. A weak or abandoned mark can end the case regardless of how similar the names are. Then we build the priority timeline from the client's own records. Then we address confusion factor by factor. Where the plaintiff's conduct supports it, we plead a cancellation counterclaim and a fee request for an exceptional case. (15 U.S.C. § 1117(a).) Lanham Act cases are heard in the Central District of California, in Santa Ana and Los Angeles; state claims may be in Superior Court.

What to bring to the first meeting

The complaint or demand letter. Everything that shows when you first used the name and that you have used it since: licenses, invoices, ads, photos, domain registrations. Evidence of the plaintiff's use, or nonuse, that you know of. Any dealings you have had with the plaintiff. And a candid account of how you chose the name and whether you knew of theirs.

Frequently asked questions

What are the defenses to trademark infringement?

No likelihood of confusion. The plaintiff's mark is generic, merely descriptive, functional, or abandoned. You used the mark first in your territory. Descriptive or nominative fair use. Laches, acquiescence, or estoppel. The statute lists several of these as defenses even to an incontestable registration. (15 U.S.C. § 1115(b).)

What is fair use of a trademark?

Descriptive fair use is using a word in its ordinary meaning to describe your own goods, in good faith and not as a brand. (15 U.S.C. § 1115(b)(4).) Nominative fair use is naming someone else's product because there is no other practical way to refer to it, using no more of the mark than needed and implying no endorsement.

What is nominative fair use?

A defense recognized in the Ninth Circuit for a defendant who uses a trademark to refer to the trademark owner's own goods or services. It applies when the product is not readily identifiable without the mark, only as much of the mark as necessary is used, and nothing suggests sponsorship. (New Kids on the Block v. News America Publishing, Inc. (9th Cir. 1992) 971 F.2d 302, 308.)

What is laches in a trademark case?

An equitable defense for a defendant harmed by the plaintiff's unreasonable delay in suing after it knew or should have known of the use. (15 U.S.C. § 1115(b)(9).) The Lanham Act has no statute of limitations. Courts use the closest state limitations period as a guide and weigh the prejudice the delay caused.

Can I use a competitor's trademark in comparative advertising?

Usually, if the comparison is truthful and you use the competitor's name only to identify its product. That is a nominative use. Using the competitor's logo or implying an affiliation moves outside the defense. False statements about the competitor's product raise a separate false advertising claim. (15 U.S.C. § 1125(a)(1)(B).)

Talk to a California trademark defense attorney

If you have been sued or threatened over a trademark, call (909) 235-6116 or contact us online. Kolmogorov Law, P.C. is at 327 Magnet, Irvine, CA 92618, and defends businesses in Orange County, Los Angeles, and throughout California. See also our IP litigation page.

This page provides general information about federal and California trademark law and is not legal advice. Outcomes depend on the history of use, the strength of the mark, and the court.