How to File a Trademark Infringement Lawsuit: Steps, Proof, and Costs

To file a trademark infringement lawsuit, you send a cease and desist letter, then file a complaint in federal district court under the Lanham Act, serve the defendant, and litigate through discovery toward settlement, summary judgment, or trial. The filing fee is $405, but attorney and expert costs are where the real money goes.¹ Federal district courts have original jurisdiction over these claims regardless of the amount in dispute or where the parties live.² Each step below has requirements that shape the strength of your case and how much it will cost.

Send a Cease and Desist Letter First

Before you file anything, put the other side on formal notice. A cease and desist letter identifies you as the trademark owner, cites your federal registration number if you have one, describes the infringing use with specific evidence (screenshots of the website, photos of the product), and demands they stop by a set deadline. Two to three weeks is typical.

Many disputes end here. Even when they don’t, the letter creates a paper trail showing you acted promptly, which matters later if the defendant argues you delayed. If the response is unsatisfactory or you hear nothing, that is the signal to move toward litigation.

Confirm Your Trademark Rights

Your case starts with proving you own valid rights. How heavy that lift is depends on whether the mark is federally registered.

A federal registration certificate from the U.S. Patent and Trademark Office is your strongest evidence. It serves as prima facie proof that the mark is valid, that you own it, and that you have the exclusive right to use it in commerce for the goods or services listed.³ Registration shifts the initial burden to the defendant to prove the mark shouldn’t be protected.

You can still sue without a federal registration. Section 43(a) of the Lanham Act lets owners of unregistered marks bring claims for false designation of origin, but you lose the statutory presumptions.⁴ You have to independently prove the mark is valid and distinctive. Fanciful marks (invented words like “Xerox”), arbitrary marks (real words in unrelated contexts, like “Apple” for computers), and suggestive marks are inherently distinctive. Descriptive marks require you to show “secondary meaning,” meaning consumers associate the term with your brand rather than its dictionary sense. Evidence of secondary meaning includes sales volume, advertising spend, consumer surveys, and unsolicited media coverage. Generic terms cannot function as trademarks at all.

Draft the Complaint

The complaint is the document that launches the lawsuit and frames the entire dispute for the court.

Parties, Jurisdiction, and Venue

You need full legal names and addresses for every plaintiff and defendant. If the infringer operates through a business entity, name the entity, and depending on the facts, the individual owners.

Federal trademark claims go to federal district court under the Lanham Act’s grant of original jurisdiction.² Venue is proper in a district where any defendant resides (if all defendants reside in the same state) or where a substantial part of the infringing activity took place.⁵ For online infringement, the second option often gives you flexibility, since the conduct may reach consumers in multiple districts.

Facts and Legal Claims

Describe your mark, when and how you have used it, your registration if applicable, and the defendant’s infringing conduct. Attach screenshots, product photos, or advertising examples as exhibits. Vague descriptions weaken the complaint.

The two most common causes of action are federal trademark infringement under 15 U.S.C. § 1114, which applies when someone uses a copy or imitation of your registered mark in commerce in a way likely to cause consumer confusion,⁶ and false designation of origin under 15 U.S.C. § 1125(a), which covers both registered and unregistered marks and reaches any use of a word, symbol, or device in commerce likely to confuse consumers about origin or sponsorship.⁴ Many plaintiffs plead both. State trademark and unfair competition claims can be added as supplemental claims in the same complaint.

What You Have to Prove: Likelihood of Confusion

Likelihood of confusion is the central question in almost every trademark infringement case. You do not need to show actual confusion, only that confusion is probable. Courts use a multi-factor test that varies slightly by circuit but generally examines:

Similarity of the marks in appearance, sound, and meaning
Similarity of the goods or services and whether the parties compete in the same or related markets
Strength of your mark, since well-known and distinctive marks get broader protection
Evidence of actual confusion, such as consumer complaints, misdirected emails, or survey data
The defendant’s intent, particularly whether they deliberately adopted a similar mark to trade on your goodwill
Marketing channels and whether both parties sell through the same outlets or advertise in the same places
Consumer sophistication, since impulse buys at low price points are more confusion-prone than expensive researched purchases

No single factor decides the case. Courts weigh them together, and a strong showing on a few can carry the day even if others are neutral. Building the record early through consumer surveys, side-by-side mark comparisons, and evidence of intent strengthens both the complaint and your position at summary judgment.

Remedies to Request

The prayer for relief tells the court what you want if you win. The Lanham Act gives courts broad discretion.

Injunctive Relief

An order stopping the defendant from using your mark is usually the most important remedy. Courts have express authority to issue injunctions against ongoing or future violations, and once you prove infringement, you are entitled to a rebuttable presumption of irreparable harm.⁷ The court can also order the defendant to file a written compliance report within 30 days.

Monetary Damages and Profits

If you prove a violation, you can recover the defendant’s profits from the infringing use, your own actual damages, and the costs of the lawsuit.⁸ The profits calculation works in your favor procedurally. You only prove the defendant’s gross sales; the defendant then bears the burden of proving costs and deductions. Courts can increase a damages award up to three times the actual amount, though the statute frames the enhancement as compensatory, not punitive.

Attorney Fees

Attorney fees are available only in “exceptional cases.”⁸ Courts look at the totality of the circumstances, including whether the losing side’s position was objectively unreasonable or whether bad faith was involved. A genuinely debatable case probably will not qualify. A case involving knowing copying followed by stonewalling might.

File and Serve the Defendant

Filing

You file by submitting the complaint to the clerk of the federal district court along with a civil cover sheet (Form JS 44) and a summons. Most courts handle this electronically through CM/ECF, which requires PDFs. The total filing fee is $405: a $350 statutory filing fee and a $55 administrative fee.¹

Service of Process

After the court issues the summons, you must formally deliver the summons and complaint to the defendant. Mailing alone does not count for most domestic defendants. Under Rule 4, you can serve an individual within the United States by personal delivery, by leaving copies at their home with a person of suitable age who lives there, or by delivering copies to an authorized agent.⁹ Service must be performed by someone at least 18 years old who is not a party. Professional process servers usually handle this, with fees running $55 to $225.

Waiver of Service

Before paying a process server, consider asking the defendant to waive formal service. You mail the complaint, two copies of the waiver form, and a prepaid return envelope. The defendant gets at least 30 days to return the signed waiver (60 days if outside the United States).⁹ Signing gives them 60 days to respond instead of the usual 21. If they refuse without good cause, the court will make them pay the expenses you incur for formal service, including attorney fees for any motion to collect those costs. Waiver does not give up the right to challenge jurisdiction or venue.

Ask for Emergency Relief When Needed

When the infringement is causing immediate and ongoing harm, waiting months for a final judgment is not practical. You can ask the court for a temporary restraining order or preliminary injunction at or shortly after filing.

You must show four things: likely success on the merits, irreparable harm without the order, that the balance of hardships tips in your favor, and that the injunction serves the public interest.¹⁰ The Lanham Act helps with the second factor. Once you demonstrate likely success on the merits, you get a rebuttable presumption of irreparable harm.⁷

A temporary restraining order can be issued quickly, sometimes the same day, and lasts up to 14 days. A preliminary injunction requires a hearing and stays in place until the case is resolved. This is the tool that stops the bleeding while the full case plays out.

The Defendant’s Response and Likely Defenses

Once served, the defendant has 21 days to file an answer, or 60 days if they signed a waiver.¹¹ The answer goes paragraph by paragraph through your complaint, admitting or denying each allegation, and raises affirmative defenses. Instead of answering, the defendant may file a motion to dismiss arguing a legal flaw such as lack of jurisdiction, improper venue, or failure to state a claim. If the court grants the motion, the case may be dismissed or you may get a chance to amend.

The most common defense is fair use. Classic fair use applies when the defendant uses your trademarked term not as a brand but in its ordinary descriptive sense. If you have trademarked “Sharp” for televisions, a competitor describing their screen as “sharp” is not infringing. The statute protects good-faith use of a descriptive term to describe someone’s own goods or their geographic origin.¹² Nominative fair use is a related judge-made concept covering situations where the defendant uses your mark to refer to your product, such as a repair shop advertising that it services your brand of equipment.

The Lanham Act has no express statute of limitations. Courts police delay through the equitable doctrine of laches. If you knew about the infringement and sat on your rights, the defendant can argue that inaction caused prejudice, perhaps because they invested heavily in building their brand while you said nothing. Courts often benchmark against the analogous state statute of limitations for fraud. Delays beyond that period create a presumption that laches applies, shifting the burden to you to explain the wait. Pre-litigation settlement talks or the defendant’s gradual expansion into your market can excuse some delay, but the safer course is to act quickly.

Additional statutory defenses include abandonment, prior use in good faith predating your rights (limited to the geographic area of continuous use), and fraud on the trademark office.¹²

Discovery, Settlement, and Summary Judgment

Shortly after the answer, both sides’ attorneys must confer under Rule 26(f) to discuss the claims, explore early settlement, and develop a discovery plan.¹³ The judge then issues a scheduling order setting deadlines for the rest of the case, and that order is hard to change without good cause.¹⁴

Discovery is where you gather evidence from the other side. Standard tools are written interrogatories, document and electronic-records requests, and depositions of witnesses under oath before a court reporter. In trademark cases, discovery focuses on the defendant’s sales records (needed to calculate profits), marketing materials, internal communications about branding decisions, and any evidence of consumer confusion. This is where costs climb. Court reporter fees run $150 to $400 per deposition plus $4.50 to $7.00 per page for transcripts, and intellectual property experts commonly charge $350 to $475 per hour.

Every federal district court must offer at least one form of alternative dispute resolution, and some require mediation or early neutral evaluation before trial.¹⁵ Participation is required; agreement is not. The vast majority of trademark lawsuits settle before trial, so take any ADR opportunity seriously.

After discovery closes, either side can move for summary judgment, arguing the undisputed facts entitle them to win as a matter of law. The court grants the motion only if no genuine dispute exists on any material fact.¹⁶ This is where your record on the likelihood-of-confusion factors gets tested. A strong showing, particularly consumer surveys and clear evidence of intent, can end the case here.

What It Actually Costs

The $405 filing fee is the smallest number in the budget. Attorney fees are the largest cost by far. Even a straightforward infringement action that settles early can run tens of thousands of dollars in legal fees. A case that goes through full discovery and trial can reach six figures. Expert witnesses, particularly the survey experts used to prove likelihood of confusion, add significant expense on top of attorney time.

Other expenses to budget for: process server fees of $55 to $225, deposition costs, electronic document review, and possibly a consumer survey. Before filing, have a candid conversation with your attorney about likely total costs at each stage, and whether a strongly worded cease and desist letter or a negotiated license might achieve the same practical result for a fraction of the expense.

1
United States Courts. District Court Miscellaneous Fee Schedule
2
Office of the Law Revision Counsel. 15 USC 1121 – Jurisdiction of Federal Courts
3
Office of the Law Revision Counsel. 15 USC 1057 – Certificates of Registration
4
Office of the Law Revision Counsel. 15 USC 1125 – False Designations of Origin, False Descriptions Forbidden
5
Office of the Law Revision Counsel. 28 USC 1391 – Venue Generally
6
Office of the Law Revision Counsel. 15 USC 1114 – Remedies; Infringement
7
Office of the Law Revision Counsel. 15 USC 1116 – Injunctive Relief
8
Office of the Law Revision Counsel. 15 USC 1117 – Recovery for Violation of Rights
9
Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons
10
Justia. Winter v. Natural Resources Defense Council, Inc., 555 U.S. 7 (2008)
11
Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections
12
Office of the Law Revision Counsel. 15 USC 1115 – Registration on Principal Register as Evidence of Exclusive Right to Use Mark; Defenses
13
Legal Information Institute. Federal Rules of Civil Procedure Rule 26 – General Provisions Regarding Discovery; Duty of Disclosure
14
Legal Information Institute. Federal Rules of Civil Procedure Rule 16 – Pretrial Conferences; Scheduling; Management
15
Federal Judicial Center. Alternative Dispute Resolution in the U.S. District Courts
16
Legal Information Institute. Federal Rules of Civil Procedure Rule 56 – Summary Judgment