When a patent holder discovers that a competitor may be making, selling, or using their patented invention without authorization, the question is simple: “what do you do next?” The answer is not so simple. Filing a patent infringement lawsuit is one of the most complex and consequential steps a patent owner can take. It involves a carefully sequenced process that begins long before any complaint is filed in court — and requires strategic decision-making, thorough investigation, and experienced legal counsel at every stage.
This article provides an overview of the key steps in that process — from monitoring the marketplace and identifying potential infringement, through due diligence, cease-and-desist letters, jurisdiction and venue selection, and ultimately bringing suit. Understanding what lies ahead helps patent holders make informed decisions about whether and how to proceed.
Understanding Patent Infringement
Patent infringement occurs when an entity makes, sells, offers for sale, uses, or imports a patented invention without the patent owner’s permission. Under U.S. patent law, this applies if the accused product or process includes every element of a patented claim or an equivalent feature. Critically, enforcement is the patent holder’s responsibility — the United States Patent and Trademark Office (USPTO) does not actively police patent rights.
There are several distinct categories of infringement, each carrying different legal implications. Direct infringement involves unauthorized manufacturing, selling, or use of the patented invention. Indirect infringement arises when a party knowingly encourages or facilitates another’s infringement (inducement) or supplies a component that has no substantial non-infringing use (contributory infringement). Willful infringement — where the defendant knowingly infringed the patent — can result in enhanced damages of up to three times the amount awarded, making it an especially important consideration both in enforcement strategy and in a defendant’s response to notice.
The Patent Infringement Lawsuit Process
Bringing a patent infringement lawsuit is a multi-stage undertaking. Each step below represents a critical decision point, and an experienced patent litigation attorney will guide the analysis and strategy at every juncture.
Step 1: Monitoring for and Identifying Potential Infringement
The first step in enforcing a patent is recognizing that infringement may be occurring. Patent holders who are actively monitoring the competitive landscape are better positioned to identify infringement early — before damages accumulate and before the infringer entrenches its market position.
Effective monitoring strategies include tracking competitor product launches, reviewing trade publications and industry conferences, watching new patent filings through the USPTO database, and setting up market surveillance for products that could infringe your patent claims. Infringement may also come to light through customer reports or distributor feedback. In some cases, a diligent review of competing products — especially after a major product launch — reveals a potential infringement issue that warrants closer examination.
Once a potential infringement is suspected, it is important to act promptly. For example, delay in notifying an infringer can limit the damages a patent holder can recover.
Step 2: Due Diligence — Assessing Validity, Infringement, and Damages
Before any enforcement action is taken, a thorough pre-litigation due diligence analysis is required. This process has several components, and an experienced patent litigation attorney will help with the assessment.
Patent validity and ownership should be confirmed at the outset. The patent must be currently in force, with all maintenance fees paid and the expiration date not yet reached. The plaintiff must also have standing to bring suit — meaning the proper ownership or exclusive license rights must be established. Complications can arise when inventions involve co-inventors, prior assignments, or licensing agreements that affect standing.
A claim mapping and infringement analysis is the next critical step. Patent litigation attorneys prepare a detailed chart comparing each element of the asserted patent claim against the accused product or process. If any claim element is absent and no equivalent can be established, the infringement theory breaks down. This analysis is the foundation for any enforcement action.
Assessing patent strength is equally important. Even a valid patent faces risks if it is susceptible to prior art challenges, obviousness arguments, or other invalidity defenses that a defendant is likely to raise. A realistic evaluation of how the patent would fare under challenge helps the patent holder calibrate the risk and cost of litigation. This analysis should also account for the defendant’s likely invalidity counterclaims and any inter partes review (IPR) petition risk — a USPTO-administered proceeding in which the validity of patent claims can be challenged.
Finally, a damages assessment should be conducted before any enforcement action is initiated. Patent litigation can cost hundreds of thousands to several million dollars to litigate through trial. If the potential damages recovery — whether through lost profits, a reasonable royalty, or injunctive relief — does not justify the cost and disruption of litigation, alternative approaches such as licensing discussions may be more appropriate.
Step 3: Gathering Evidence of Infringement
A strong evidentiary record is essential to a successful patent infringement case. The plaintiff bears the burden of proving infringement by a preponderance of the evidence, and the quality of the pre-suit evidence can significantly affect both the outcome of the case and the parties’ respective leverage in settlement negotiations.
Evidence gathered at this stage typically includes product samples or reverse-engineered analysis of the accused product, product specifications, user manuals, and marketing materials from the alleged infringer, publicly available technical documentation and sales data, and where possible, expert analysis or technical evaluations comparing the accused product to the patent claims. This documentation supports both the claim chart developed in Step 2 and any damages calculation.
Step 4: Cease-and-Desist Letters and Pre-Suit Negotiations
In many patent disputes, the first formal step is sending a cease-and-desist (C&D) letter to the alleged infringer. This letter serves several important legal purposes that go well beyond simply asking the other party to stop. It is a strategic document that must be carefully drafted by experienced patent counsel.
A properly drafted C&D letter identifies the patent(s) at issue, describes the specific infringing product or conduct, and demands that the infringement cease. It also places the alleged infringer on formal notice of the patent and the alleged infringement. This notice matters significantly: once a party has been notified of infringement, any continued infringement may be deemed willful, which can support enhanced damages of up to three times the compensatory award if the case proceeds to litigation.
Some patent disputes are resolved at the pre-litigation stage through licensing negotiations. The C&D letter may open a dialogue in which the parties negotiate a royalty-bearing license, a cross-license, or a settlement that compensates the patent holder without resort to costly litigation.
Step 5: Jurisdiction and Venue Selection
Federal district courts have exclusive jurisdiction over patent infringement cases under 28 U.S.C. § 1338. Choosing where to file, however, is one of the most strategically significant decisions in the entire litigation process.
Patent venue was dramatically reshaped by the U.S. Supreme Court’s 2017 decision in TC Heartland LLC v. Kraft Foods Group Brands LLC, which significantly curtailed “forum shopping” by patent plaintiffs. Under current law, a domestic corporate defendant may only be sued in a district where the defendant is incorporated, or where the defendant has committed acts of infringement and has a regular and established place of business. This means the choice of forum for many cases is now constrained by where the defendant operates, not simply wherever the plaintiff files.
Within proper venue options, strategic considerations include the court’s patent docket experience and speed to trial, the local rules and judges’ tendencies on key issues such as claim construction and summary judgment, the availability of a local jury pool with technological sophistication, and proximity to key witnesses and evidence. Counsel experienced in patent litigation will evaluate these factors carefully before recommending a filing venue.
At this stage, consideration should also be given to whether to seek a temporary restraining order (TRO) or preliminary injunction to halt the infringing activity while the lawsuit is pending. Obtaining a preliminary injunction in patent cases is challenging — it requires showing, among other things, a likelihood of success on the merits and irreparable harm — but in certain cases, particularly where the infringement threatens to cause irreparable market damage, it can be a critical tool.
Step 6: Filing the Complaint
When pre-litigation efforts do not resolve the dispute, the patent holder files a complaint in the chosen federal district court. The complaint initiates the lawsuit and must satisfy the pleading standards of the Federal Rules of Civil Procedure. It should clearly identify the plaintiff and defendants, identify the patent(s) at issue and their ownership, describe the infringing products or processes with sufficient specificity, allege the basis for the court’s jurisdiction and venue, and set forth the relief sought — which typically includes monetary damages, an injunction, attorneys’ fees in exceptional cases, and any applicable enhanced damages.
The complaint should be well-drafted from the outset. The groundwork laid in Steps 2 through 5 — the claim analysis, evidence gathering, and venue selection — directly informs the quality of the complaint.
Step 7: The Litigation Process
Once the complaint is filed and served, patent litigation proceeds through several stages that can span years. The defendant will have an opportunity to respond to the complaint, which often includes counterclaims asserting that the patent is invalid or not infringed. The parties will then engage in discovery — a period of extensive document exchange, depositions, and expert disclosures — which is frequently the most time-consuming and expensive phase of the case.
A Markman hearing — in which the court construes the meaning of the patent claims — is a pivotal milestone unique to patent cases and often significantly shapes the litigation’s trajectory. Following claim construction, the parties typically file motions for summary judgment. The case may be resolved at that stage, or it may proceed to a jury trial. If the patent holder prevails, the court may award monetary damages, enhanced damages for willful infringement, injunctive relief barring continued infringement, and attorneys’ fees in exceptional cases. Post-trial motions and appeals to the Federal Circuit may follow.
Settlement remains possible at any point throughout the litigation, and many patent cases resolve through negotiated licenses or settlements before or during trial. Skilled patent litigation counsel will continually assess settlement opportunities alongside the litigation strategy throughout the case.
Work with Allen Dyer’s Patent Litigation Team
Deciding to pursue a patent infringement lawsuit is not a decision to be taken lightly. It requires careful analysis of the patent’s strength, the strength of the infringement case, the potential recovery, and the risks — including invalidity counterclaims and the cost of litigation. A misstep at any stage, from a poorly timed C&D letter to a poorly chosen venue, can undermine an otherwise strong case.
At ADD + G, our patent litigation team has decades of experience enforcing and defending patent rights before federal courts throughout the United States. We bring both deep technical knowledge and formidable courtroom experience to every case, and we work closely with each client to develop an enforcement strategy that aligns with their business objectives. If you believe your patent rights are being infringed, contact us today to schedule a consultation.
About the Author
John Woodson is a Registered Patent Attorney who practices in the area of patent prosecution, patent infringement studies and client counseling. His patent prosecution experience includes electrical and electronic equipment, telecommunications equipment, laser and optical devices, semiconductor devices, semiconductor processing, hydrocarbon recovery and well logging, mechanical devices, medical devices, and software and Internet related inventions.