Trademark Infringement Litigation: Proof, Defenses, and Damages

Trademark infringement litigation is the federal court process for stopping someone from using a mark confusingly similar to yours and recovering the money their use cost you. The claim lives under the Lanham Act, the central question is whether consumers are likely to confuse the two sources, and the available remedies run from a court order halting the infringing use to disgorgement of the defendant’s profits, enhanced damages, and in some cases attorney fees. These are expensive cases. They are also, when the facts are right, one of the few tools that actually makes an infringer stop.

What You Have to Prove

The Lanham Act gives you two tracks. If your mark is federally registered, anyone who uses a confusingly similar mark in commerce is liable to you in a civil action.¹ If your mark is unregistered, a parallel provision reaches anyone who uses a false designation of origin likely to confuse consumers about the source of goods or services.² The practical difference matters. A federal registration gives you a presumption of validity and nationwide priority. Without one, you have to prove both through your own evidence of use.

Either way, the center of the case is likelihood of confusion. Courts work through a multi-factor test, called the Polaroid factors in the Second Circuit and the DuPont factors at the USPTO and in other circuits. The labels change; the ground covered does not:

Similarity of the marks in appearance, sound, meaning, and overall commercial impression.
Strength of the plaintiff’s mark. Coined or fanciful marks get broader protection than descriptive ones.
Proximity of the goods or services. Shared categories or retail channels make confusion more plausible.
Evidence of actual confusion, such as misdirected emails, customer complaints, or survey data.
The defendant’s intent, including whether the defendant adopted the mark to trade on the plaintiff’s reputation.
Consumer sophistication. A buyer spending thousands on industrial equipment reads brands more carefully than someone grabbing a product at the checkout counter.

No single factor decides the case. A mark that looks nothing like yours can still create confusion if both products sit on the same shelf and chase the same customers. Courts weigh the factors together, which is why outcomes are hard to predict and why discovery drives these cases.

A Separate Claim for Famous Marks

If your mark is famous to the general consuming public across the United States, you can also sue for dilution, and dilution does not require any showing of consumer confusion. The owner of a famous mark can obtain an injunction against a later-adopted mark likely to dilute the famous mark through blurring, which weakens its distinctiveness, or tarnishment, which associates it with low-quality or unsavory goods. The fame bar is deliberately high. Marks known only within a niche market rarely clear it. Dilution claims also cannot reach fair uses, including comparative advertising, parody, criticism, news reporting, and noncommercial use.²

The Evidence You Need Before You File

Start with proof of your own rights. If the mark is federally registered, order a certified copy of the registration certificate from the USPTO. The fee is $15 for a standard certified copy, or $30 expedited.³ That certificate is strong presumptive evidence of validity and of your exclusive right to use the mark nationwide. If the mark is unregistered, you have the heavier job of compiling dated advertisements, invoices, packaging, and promotional materials showing when and where you first used the mark in commerce.

Next, document the infringement. Capture screenshots of the defendant’s website, photograph the products and packaging, save marketing materials, and timestamp every file. A folder of captures taken over months is far more persuasive than a single screenshot. It shows the use was sustained rather than a one-off mistake.

Evidence of actual consumer confusion is where many of these cases are won. Save emails and social media messages from customers who mixed up the brands, misdirected orders, confused service calls. A professionally designed consumer survey can supply quantitative proof that a meaningful share of relevant buyers associates the defendant’s mark with your company. Surveys are powerful, but they have to follow accepted methodologies. Courts regularly reject survey results built on leading questions or flawed designs.

Financial records close the file. A decline in sales, a lost licensing deal, or a spike in customer service costs that lines up with the defendant’s market entry strengthens both liability and damages.

Before You File

A federal lawsuit is not always the right opening move. Most trademark owners begin with a cease-and-desist letter demanding that the infringer stop using the mark. A well-drafted letter often ends the dispute, especially when the other side simply didn’t know. The risks are real, though. The recipient can file a declaratory judgment action in a court of their choosing, pulling you onto their home turf. Aggressive letters sometimes go viral, and a company cast as a bully over a weak claim can take genuine reputational hits.

Mediation is the other off-ramp. A mediator can help both sides reach outcomes a court cannot order, such as a license, a geographic split of the market, or a phased transition away from the disputed mark, and it costs a fraction of litigation. Many federal courts require at least an attempt at settlement before trial, so starting early gets you ahead on that front.

One boundary worth noting. If your dispute is really about the right to register a mark rather than the right to use it, the Trademark Trial and Appeal Board at the USPTO handles opposition and cancellation proceedings. The TTAB can block or cancel a registration. It cannot award damages or order the defendant to stop selling. If you need the infringer to stop and pay, federal district court is the only path.

How the Lawsuit Runs

Picking the Court

A trademark case can be filed where the defendant resides or where a substantial part of the infringing activity happened.⁴ For a corporate defendant, “resides” means any district where the company is subject to personal jurisdiction. When a competitor sells through a national website, several districts may qualify. The choice affects local rules, the available judges, and the jury pool, which makes venue one of the most consequential early calls.

Filing, Service, and Response

The case opens with a civil complaint laying out the facts, identifying the Lanham Act provisions at issue, and specifying the relief you want. The statutory filing fee for a federal civil action is $350, plus administrative fees set by the Judicial Conference.⁵ Filings go through the court’s electronic case management system.

After filing, you have 90 days to serve the summons and complaint. Miss that window without good cause and the court can dismiss.⁶ The defendant then has 21 days from service to answer or file a motion to dismiss.⁷ If nothing comes back at all, you can move for default judgment.

Discovery and Trial

Once the pleadings close, discovery opens. Both sides exchange documents, answer written interrogatories, and take depositions. In trademark cases, discovery leans hard on the defendant’s marketing files, sales records, customer communications, and internal documents that reveal whether the similar mark was adopted on purpose. Discovery usually runs several months, longer in cases with multiple product lines or international sales.

After discovery, either side can move for summary judgment, asking the judge to decide the case without trial because the key facts are not actually disputed. Many trademark cases end there. If material facts are genuinely in dispute, the case goes to trial before a judge or jury, where likelihood of confusion plays out through testimony, surveys, and expert opinion.

How Long You Can Wait

The Lanham Act does not include a statute of limitations for infringement. Courts have historically filled the gap by borrowing the limitations period from the closest state-law claim, generally landing somewhere between three and six years, though not every circuit follows that approach and at least one has rejected it.

In practice, the equitable defense of laches does the work. A defendant invokes laches by showing you waited unreasonably long to file and the delay caused them prejudice. If the court agrees, it can bar part or all of your claims. The lesson is simple. There is no hard deadline, but sitting on your rights while an infringer builds a business around your mark is a reliable way to lose.

What the Defendant Will Argue

The Lanham Act lists several defenses, and courts have added more through case law. Knowing which ones apply shapes both strategy and settlement value.

Fair Use

Descriptive fair use lets someone use a trademarked term in its ordinary descriptive sense rather than as a brand. A bakery can describe its bread as “hearty” even if another company owns a registration on “Hearty” for baked goods, as long as the use is descriptive and in good faith. The statute protects use of a term “fairly and in good faith only to describe” the defendant’s own goods or their geographic origin.⁸

Nominative fair use is a separate, court-created doctrine that lets a party use someone else’s mark to refer to that party’s actual product. A phone repair shop advertising iPhone repairs, or a reviewer comparing two named brands, is relying on it. The test asks whether the product was identifiable without the mark, whether the defendant used only as much of the mark as needed, and whether anything about the use suggested sponsorship or endorsement.⁹

Abandonment and Genericness

A mark the owner stops using, with no intent to resume, can be declared abandoned and loses protection. Three consecutive years of nonuse is generally treated as presumptive evidence of abandonment.⁸ A defendant can also argue the mark has gone generic, meaning the public now uses the term for a type of product rather than a specific source. Escalator, aspirin, and thermos all started as trademarks and lost protection that way. Once a court declares a mark generic, anyone can use it.

Prior Use and Statutory Defenses

A defendant who adopted the mark without knowledge of the plaintiff’s use, and has used it continuously since before the plaintiff’s registration date, has a limited defense in the geographic area where that prior use is established. Other statutory defenses include fraud on the USPTO during registration and misrepresentation of source.

What You Can Win

Injunctions

For most trademark owners, the injunction is the point of the case. A permanent injunction orders the defendant to stop using the mark. Federal courts have broad authority to grant one, and a plaintiff who proves infringement gets a rebuttable presumption that continued infringement would cause irreparable harm.¹⁰ That presumption matters, because irreparable harm had long been one of the hardest elements to establish.

You can also seek a preliminary injunction early in the case to stop the infringer while the litigation plays out. The court weighs four factors together: likelihood of success on the merits, likelihood of irreparable harm without the injunction, the balance of equities, and the public interest. The same statutory presumption of irreparable harm applies when you show a likelihood of success.¹⁰

The Defendant’s Profits and Your Damages

Monetary recovery comes from two pools: your own losses and the defendant’s profits. To reach the defendant’s profits, you only need to prove the defendant’s gross sales. The defendant then carries the burden of proving any costs or deductions.¹¹ That burden-shift matters because infringers often keep thin records and have every incentive to inflate costs.

The court can also enhance the damages award to up to three times the actual damages amount. The enhancement is framed as compensation rather than a penalty, and it does not strictly require a finding of willfulness, though bad faith makes it far more likely.¹¹

Counterfeiting

Counterfeiting carries a tougher remedial track. When a defendant intentionally uses a counterfeit mark, the court must award three times the profits or damages, whichever is greater, plus reasonable attorney fees, absent extenuating circumstances.¹¹ The “must” is what distinguishes counterfeiting from ordinary infringement, where enhancement is discretionary.

A plaintiff in a counterfeiting case can also elect statutory damages in place of proving actual losses. The standard range is $1,000 to $200,000 per counterfeit mark per type of goods sold. For willful counterfeiting, the ceiling rises to $2,000,000 per mark per type of goods.¹¹ Statutory damages become especially useful when the counterfeiter’s financial records are unreliable or missing, which is the norm in these operations.

Attorney Fees and Destruction

In “exceptional cases,” the court can award reasonable attorney fees to the prevailing party.¹¹ Deliberate copying, litigation misconduct, and frivolous defenses are the common triggers. Fee awards in trademark cases can easily exceed $100,000 given the length and complexity of the work.

Finally, the court can order destruction of all infringing labels, packaging, advertisements, and the molds or plates used to produce them.¹² That remedy keeps the infringer from warehousing stock and resuming sales once the case ends.

1
Office of the Law Revision Counsel. 15 USC 1114 – Remedies; Infringement; Innocent Infringement by Printers and Publishers
2
Office of the Law Revision Counsel. 15 USC 1125 – False Designations of Origin, False Descriptions, and Dilution Forbidden
3
United States Patent and Trademark Office. USPTO Fee Schedule
4
Office of the Law Revision Counsel. 28 USC 1391 – Venue Generally
5
Office of the Law Revision Counsel. 28 USC 1914 – District Court; Filing and Miscellaneous Fees; Rules of Court
6
Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons
7
Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections
8
Office of the Law Revision Counsel. 15 USC 1115 – Registration on Principal Register as Evidence of Ownership
9
Ninth Circuit Model Civil Jury Instructions. Trademark Infringement – Defenses – Nominative Fair Use
10
Office of the Law Revision Counsel. 15 USC 1116 – Injunctive Relief
11
Office of the Law Revision Counsel. 15 USC 1117 – Recovery for Violation of Rights
12
Office of the Law Revision Counsel. 15 USC 1118 – Destruction of Infringing Articles