Unregistered Trademarks: Suing Without a Registration in California

Last updated: November 2026

Yes, you can sue for trademark infringement without a registration. Trademark rights come from use in commerce, not from a certificate, and section 43(a) of the Lanham Act gives the owner of an unregistered mark a federal claim against confusing use. (15 U.S.C. § 1125(a)(1)(A).) California's trademark statute preserves common law trademark rights as well. (Bus. & Prof. Code, § 14259.) The unregistered owner must prove more, and its rights end at its market's edge. Kolmogorov Law, P.C. litigates these claims for Orange County and Los Angeles businesses.

Call (909) 235-6116 or contact us online if someone is using a name you built but never registered.

Where common law trademark rights come from

A trademark is any word, name, symbol, or device used to identify and distinguish one person's goods from those sold by others. (15 U.S.C. § 1127.) The right arises when the mark is actually used in the ordinary course of trade, on goods that are sold or transported, or in the sale or advertising of services that are rendered. (15 U.S.C. § 1127.) Nothing in that definition mentions a filing. A bakery that has sold under one name for twelve years owns that name, in its market, whether or not it ever heard of the Patent and Trademark Office.

The mark also has to be distinctive. A coined or arbitrary name is distinctive from the first sale. A descriptive name, one that tells the customer what the product is or does, is protected only once the buying public has come to associate it with a single source. Lawyers call that secondary meaning. That proof is often the whole case for an unregistered mark.

What an unregistered trademark owner must prove that a registrant does not

A registration on the principal register is prima facie evidence of the mark's validity, the registrant's ownership, and its exclusive right to use the mark on the listed goods. (15 U.S.C. §§ 1057(b), 1115(a).) The unregistered owner has to prove each of those from scratch: that it used the mark first, that it has used it continuously, and that the mark is distinctive, inherently or through secondary meaning.

Unregistered trade dress carries one more burden. The plaintiff must prove that the design or packaging it claims is not functional. (15 U.S.C. § 1125(a)(3).)

Once ownership and validity are shown, the test for infringement is the same one that applies to registered marks: whether the defendant's use is likely to cause confusion about source, sponsorship, or affiliation. (15 U.S.C. § 1125(a)(1)(A).) Our page on proving infringement covers the factors.

The geographic limit

This is the real cost of not registering. Common law rights extend only to the area where the mark is used and known, plus a zone of natural expansion. A registration, by contrast, gives constructive use nationwide as of the application's filing date, contingent on the mark registering. (15 U.S.C. § 1057(c).) A later registrant cannot take away a prior user's rights in the territory where that user was already operating, but the prior user is confined to that territory. (15 U.S.C. §§ 1057(c)(1), 1115(b)(5).)

So a restaurant group known across Orange County can stop a copycat in Irvine. It may not be able to stop one in Sacramento, and if the Sacramento operator registers first, the Orange County group's expansion north is likely blocked.

How these cases come up

A contractor has operated under a family name for twenty years. A newcomer in the next city adopts the same name, registers it federally, and sends the original a cease and desist letter. The original user has the priority defense in its own area and may have grounds to cancel the registration.

A franchise-style brand grew from one shop to six across two counties without a registration. A former employee opens under a name that differs by a letter. The brand sues under section 43(a) on its common law rights, with the six locations, the reviews, and the advertising as the evidence of reputation.

An online seller has used a product name for three years but sells nationally. Here the common law rights are wide but thin, and secondary meaning in every market is hard to prove. Registering, even now, is the first advice.

Claims available in California

The federal claim is section 43(a). (15 U.S.C. § 1125(a)(1)(A).) Federal courts hear it regardless of the amount in controversy. (15 U.S.C. § 1121(a).) The California Model State Trademark Law provides its own infringement action only for marks registered with the Secretary of State. But it expressly preserves the rights, and the enforcement of rights, in marks acquired in good faith at common law. (Bus. & Prof. Code, § 14259.) The common law claim and an unfair competition claim under the UCL can be joined in Superior Court or added to the federal case. (Bus. & Prof. Code, § 17200.)

Should you register now?

Usually, yes, and the dispute is often what prompts it. A registration filed during a dispute does not change who used the mark first, but it starts the clock on nationwide priority and strengthens every later enforcement step. We handle trademark litigation; registration is a filing matter that our trademark registration guide explains, and we coordinate with filing counsel where a case calls for it.

What to bring to the first meeting

The earliest dated evidence of your use: the first invoice, the first ad, a domain registration, a lease with the name on it, photographs with dates. Evidence of continuous use since. Evidence of reputation: reviews, press, advertising spend, customer counts by city. Examples of the other side's use. And any letter you have sent or received. For the courts and the practicalities, see our Orange County trademark lawyer page.

Frequently asked questions

Can you sue for trademark infringement without registration?

Yes. Section 43(a) of the Lanham Act protects unregistered marks against confusing use, and California preserves common law trademark rights. (15 U.S.C. § 1125(a)(1)(A); Bus. & Prof. Code, § 14259.) You must prove ownership through prior use and that the mark is distinctive, which a registrant gets as a presumption.

What are common law trademark rights?

Rights in a name, logo, or design that arise from actual use in commerce rather than from a registration. They belong to the first user and extend to the territory where the mark is used and recognized. They can be enforced in federal and state court, but they do not carry the nationwide priority that a federal registration provides.

How do you prove a common law trademark?

With dated evidence of first use and continuous use, and evidence that customers associate the mark with your business: sales by location, advertising, reviews, press, and, in a large case, a consumer survey. For a descriptive name you must prove secondary meaning. For unregistered trade dress you must also prove the design is not functional. (15 U.S.C. § 1125(a)(3).)

Does using the TM symbol give me trademark rights?

No. The symbol signals that you claim the name as a mark, which can help show you used it as a brand rather than descriptively. It creates no rights by itself. Use does. The registered symbol, by contrast, may be used only for a mark that is actually registered.

What does a federal registration add if I already have common law rights?

Prima facie evidence of validity and ownership, nationwide constructive use from the filing date, the ability to become incontestable after continued use, and the statutory remedies reserved for counterfeits of registered marks. (15 U.S.C. §§ 1057(b), (c), 1115.) It also makes online takedown requests and customs recordation workable.

Talk to a California trademark litigation attorney

If a competitor is trading on a name you built, registered or not, call (909) 235-6116 or contact us online. Kolmogorov Law, P.C. is at 327 Magnet, Irvine, CA 92618, and represents businesses in Orange County, Los Angeles, and throughout California. See also our IP litigation page and our guide to trademark defenses.

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.