Trademark infringement cases are federal lawsuits in which a brand owner claims that someone else is using a confusingly similar name, logo, or other identifier without permission. These disputes are governed primarily by the Lanham Act, which protects both registered and unregistered marks. To win, a plaintiff generally has to prove two things: that they own a valid, protectable mark, and that the defendant’s use of a similar mark is likely to confuse consumers about who makes or sponsors the product.
What the Plaintiff Has to Prove
The Lanham Act gives brand owners two routes. Section 1114 of Title 15 covers marks registered with the U.S. Patent and Trademark Office, and Section 1125(a) protects unregistered marks that have built recognition through use.1Office of the Law Revision Counsel. 15 U.S. Code 1114 – Remedies; Infringement; Innocent Infringement by Printers and Publishers Under either provision, the plaintiff needs to show three things: the mark is valid and legally protectable, the plaintiff owns it, and the defendant’s use creates a likelihood of confusion.2Cornell Law Institute. Trademark Infringement
A mark qualifies for protection when it is distinctive enough that consumers associate it with a particular source. Inherently distinctive marks — coined words like “Xerox” or suggestive names like “Coppertone” — get protection automatically. Descriptive marks have to clear a higher bar: the owner must show the public has come to associate the term with their specific product, a concept called secondary meaning.
Federal registration on the Principal Register is a significant advantage. It creates a legal presumption that the mark is valid and that the registrant has the exclusive right to use it nationwide.3Office of the Law Revision Counsel. 15 U.S. Code 1115 – Registration on Principal Register as Evidence of Exclusive Right to Use Mark; Defenses You can still sue without a registration — using a mark in commerce creates common law rights — but those rights are limited to the geographic area where you actually do business.4United States Patent and Trademark Office. Why Register Your Trademark A registration certificate makes enforcement considerably easier because it functions as proof of ownership in court.
How Courts Measure Likelihood of Confusion
The central question in most trademark cases is whether consumers are likely to mistake the defendant’s product for the plaintiff’s, or believe the two are connected. Courts don’t rely on instinct. Every federal circuit has developed its own named multi-factor test: the Second Circuit uses the Polaroid factors, the Ninth Circuit applies Sleekcraft, and so on. The specific factors vary by circuit, but the same themes recur.
The common factors include:
- Strength of the plaintiff’s mark. A highly distinctive or famous mark gets wider protection because any similar use is more likely to cause confusion.
- Similarity of the marks. Courts compare how they look, sound, and feel in the overall commercial impression they leave.
- Proximity of the products. Two running shoe brands compete far more directly than a running shoe brand and a software company.
- Evidence of actual confusion. Customer testimony, misdirected emails, and wrong-number calls carry real weight.
- The defendant’s intent. If the defendant picked a similar mark to ride the coattails of an established brand, courts take that seriously.
- Consumer sophistication. Buyers spending thousands on industrial equipment research more carefully than someone grabbing a snack at a convenience store.
No single factor decides the case. A court weighs them together, and a weak showing on one can be made up by strength on others. Evidence of actual confusion is particularly persuasive, but it isn’t required. The plaintiff only has to show confusion is likely, not that it has already happened.
Confusion Before the Sale
Confusion doesn’t have to happen at the moment of purchase. Courts also recognize initial interest confusion, where a consumer is drawn to a product because a similar mark caught their attention, even if the mistake is cleared up before buying. The modern example involves online search: a competitor bids on your brand name as a keyword, and consumers click on the competitor’s ad thinking it’s yours. The theory remains more controversial than traditional point-of-sale confusion, but several circuits treat it as actionable.
Dilution: A Separate Claim for Famous Marks
Owners of truly famous marks have a second claim that doesn’t require confusion at all. Under 15 U.S.C. § 1125(c), the owner of a famous mark can sue for dilution even when there is no competition between the products and no consumer confusion.5Office of the Law Revision Counsel. 15 USC 1125 – False Designations of Origin, False Descriptions, and Dilution Forbidden The threshold for “famous” is steep: the mark must be widely recognized by the general consuming public of the United States. Courts look at the duration and reach of advertising, sales volume, and public recognition.
Dilution takes two forms. Blurring is when someone uses a similar mark on unrelated products in a way that gradually weakens the mental link between the famous mark and its source. Think of a hypothetical “Kodak” piano brand. No one confuses cameras with pianos, but the uniqueness of the Kodak name is diluted. Tarnishment is when someone uses a similar mark in a way that damages the famous mark’s reputation, typically by linking it to low-quality or unsavory goods.5Office of the Law Revision Counsel. 15 USC 1125 – False Designations of Origin, False Descriptions, and Dilution Forbidden The statute carves out exceptions for fair use (including comparative advertising and parody), news reporting, and noncommercial use. Most marks, even well-known regional brands, don’t meet the general-consuming-public fame standard, so dilution claims are narrower in practice than they look on paper.
Who Can Be Sued
The company that physically puts an infringing mark on products is the obvious defendant, but liability reaches further. Federal courts recognize two secondary theories that pull in parties who never touched the mark themselves.
Contributory infringement applies in two situations: when a party intentionally encourages the infringement, or when it keeps supplying products or services to someone it knew or should have known was infringing.6Cornell Law Institute. Contributory Infringement This theory matters a lot in e-commerce. Online marketplaces that receive specific notice that a seller is offering counterfeits and fail to act face contributory liability. Platforms aren’t required to police every listing proactively, but once they have actual knowledge of specific infringement, looking the other way creates exposure.7United States Patent and Trademark Office. Secondary Trademark Infringement Liability in the E-Commerce Setting
Vicarious infringement applies when a party has the authority to control the infringer’s activities and profits financially from the infringement.8Cornell Law Institute. Vicarious Infringement Here, knowledge isn’t the point. What matters is that the defendant had the power to stop the infringement and chose not to, while benefiting from it. The classic example is a flea market operator who collects booth fees from vendors selling counterfeits and has the right to evict them. The operator doesn’t need to know about specific counterfeits — the ability to supervise plus a financial stake is enough.
Defenses That Can Defeat the Claim
Defendants have several well-established defenses, and the right one can defeat a claim entirely even when the marks really do look alike.
Descriptive Fair Use
Federal law allows someone to use a term that happens to be trademarked if they’re using it descriptively to identify their own goods or services (not as a brand name) and doing so in good faith.9Office of the Law Revision Counsel. 15 USC 1115 – Registration on Principal Register as Evidence of Exclusive Right to Use Mark; Defenses A hotel called “The Beach” can’t stop a competitor from describing its own property as being “on the beach.” The competitor is using the word as a plain-English description, not as a brand.
Nominative Fair Use
Sometimes you have to use someone else’s trademark to identify their product. A computer repair shop advertising “We fix Dell laptops” is using the Dell mark, but there’s no reasonable way to describe the service without it. Courts evaluate three things: whether the product could be identified without using the mark, whether the defendant used only as much of the mark as necessary, and whether the use implied sponsorship or endorsement by the trademark owner.10United States Courts for the Ninth Circuit. Defenses – Nominative Fair Use
Genericness
A mark that has become the common name for a product category loses protection entirely. “Aspirin,” “escalator,” and “thermos” were all once trademarks. Any party can petition to cancel a registration on the grounds that a mark has gone generic, and the test looks at the primary significance of the term to the relevant public.11Office of the Law Revision Counsel. 15 USC 1064 – Cancellation of Registration If most people use “velcro” to mean any hook-and-loop fastener regardless of manufacturer, the mark is in trouble.
Laches
A trademark owner who sits on their rights for an unreasonably long time after learning about infringement risks losing the ability to sue. This equitable defense, called laches, requires the defendant to show the delay was inexcusable and that it caused real prejudice — for example, the defendant built a substantial business around the mark during the years the owner stayed silent. The Lanham Act has no express statute of limitations, so courts use laches as the primary timing defense and often look to analogous state statutes of limitations as a benchmark.
Before Filing: The Cease and Desist Letter
Most trademark disputes never see a courtroom. The standard first move is a cease and desist letter — a formal demand that the infringer stop. A well-drafted letter identifies the trademark (with registration details where applicable), describes the specific infringing use with evidence, explains why the use causes confusion, and sets a deadline for compliance, typically 10 to 30 days. Send it in a way that creates a record of delivery, such as certified mail with return receipt.
This step matters for reasons beyond courtesy. The letter establishes that the defendant had actual notice of the owner’s rights, which becomes important if the case goes to trial. Willful infringement, meaning continuing after you know about the other party’s rights, triggers harsher remedies. On the other side, receiving a cease and desist letter gives the recipient the option to file a declaratory judgment action, asking a court to rule that their use is lawful. That lets the accused party pick the forum rather than wait to be sued on the trademark owner’s home turf.
Remedies: What a Winning Plaintiff Gets
Injunctions
For many trademark owners, the most valuable remedy isn’t money. It’s a court order forcing the infringer to stop. The Lanham Act gives federal courts broad authority to issue injunctions, and the 2020 Trademark Modernization Act strengthened plaintiffs’ hand by creating a rebuttable presumption of irreparable harm. For a preliminary injunction or temporary restraining order, a plaintiff who shows a likelihood of success on the merits now benefits from this presumption. For a permanent injunction, the presumption kicks in once the court finds an actual violation.12Office of the Law Revision Counsel. 15 USC 1116 – Injunctive Relief
Preliminary injunctions and TROs are where urgency lives. A trademark owner who finds counterfeit goods flooding the market can’t wait two years for trial. A TRO can issue within days, sometimes without the defendant being notified in advance if the situation is urgent enough. The court balances the likely harm to the plaintiff against the burden on the defendant, considers whether money damages would be adequate, and weighs the public interest. With the presumption of irreparable harm in place, plaintiffs no longer have to independently prove money alone won’t fix the problem — the court assumes it won’t unless the defendant can show otherwise.
Monetary Damages
When money is appropriate, the Lanham Act allows a prevailing plaintiff to recover the defendant’s profits from the infringement, the plaintiff’s own actual damages, and the costs of bringing the lawsuit.13Office of the Law Revision Counsel. 15 USC 1117 – Recovery for Violation of Rights The court has discretion to adjust the profit-based recovery upward or downward if the initial figure seems inadequate or excessive, so long as the final amount is “just.” The court can’t award more than three times the actual damages found.
Counterfeiting Cases Hit Harder
Cases involving counterfeit marks run on a stricter framework. Unless the court finds extenuating circumstances, it must award three times the defendant’s profits or three times the plaintiff’s damages, whichever is greater, along with reasonable attorney fees.13Office of the Law Revision Counsel. 15 USC 1117 – Recovery for Violation of Rights Plaintiffs in counterfeit cases can also elect statutory damages instead of proving actual losses. The range is $1,000 to $200,000 per counterfeit mark per type of product sold. If the counterfeiting was willful, the ceiling jumps to $2,000,000 per mark per product type. Statutory damages are often the practical choice when the infringer’s financial records are unreliable or the plaintiff’s actual losses are hard to quantify.
Attorney Fees
Attorney fees are not automatic. The Lanham Act limits fee-shifting to “exceptional cases.”13Office of the Law Revision Counsel. 15 USC 1117 – Recovery for Violation of Rights Federal courts have broadly adopted the standard from the Supreme Court’s patent decision in Octane Fitness, treating a case as exceptional when it stands out from the norm based on the losing party’s litigation position or the unreasonable way the case was pursued. In practice, fees are most likely in cases involving deliberate copying, litigation misconduct, or claims that were objectively baseless.
Destruction of Infringing Goods
A court can also order the physical destruction of all infringing labels, packaging, advertisements, and the equipment used to produce them.14Office of the Law Revision Counsel. 15 U.S. Code 1118 – Destruction of Infringing Articles This stops the infringer from quietly resuming operations once the lawsuit ends and pulls counterfeit products out of the supply chain.
Evidence to Collect Before You File
Trademark litigation lives on evidence, and the time to start collecting it is before you file anything. The strongest cases rest on documentation of both the plaintiff’s ownership and the defendant’s wrongful use.
On ownership, a federal registration certificate is the strongest asset. It proves when the mark was registered, what goods and services it covers, and who owns it. Without a registration, you need to establish priority through other evidence: dated invoices, early advertisements, shipping records, and anything else showing when you first used the mark commercially. The USPTO’s online databases are publicly searchable and useful for checking the registration status and ownership history of both your mark and the defendant’s.
On the infringement side, gather physical and digital evidence of the defendant’s use. Screenshot their website, save their social media ads, photograph product packaging, and preserve promotional materials showing the infringing mark. Date-stamped evidence matters because you may need to prove when the infringement began.
Evidence of actual consumer confusion is especially valuable. Save emails from customers who contacted you by mistake, transcripts of misdirected service calls, and social media posts where people mix up the brands. Professional consumer surveys can provide statistical confusion data, though they’re expensive and courts scrutinize their methodology closely. A poorly designed survey can do more harm than good; a well-executed one can be the most persuasive evidence in the case.