Patent Infringement Analysis

How is a Patent Infringed?

Patent infringement analysis is the process of determining whether a product or process infringes an existing patent. In the United States, patents grant inventors exclusive rights to their inventions for a limited time, and infringing those rights can lead to costly patent litigation and payment of damages to the patentee. Understanding how to analyze patent infringement risks is necessary for making informed decisions on product development and avoiding legal action. This article provides an overview of patent infringement analysis to help businesses identify potential infringement issues and manage infringement risks.

Understanding Patent Rights and Claims

A patent gives its owner the right to exclude others from making, using, selling, or importing the patented invention. These exclusive rights are defined by the patent’s claims, which describe the scope of the patented invention. In essence, the claims set the legal boundaries of what the patent covers. An enforceable patent allows the patent holder to stop others from practicing the claimed invention. Under 35 U.S.C. § 271, patent infringement occurs when someone, without permission, makes, uses, sells, offers to sell, or imports a product or process that contains every element or an equivalent of each element of at least one patented claim while the patent is valid. This means a patent owner can assert infringement if an accused product or process falls within the scope of any claim of their patented invention.

Why Patent Infringement Analysis Matters

Performing a patent infringement analysis is important due diligence for companies launching a new product or technology. By analyzing existing patents, businesses can identify patents that might pose potential infringement risks and design around them or seek licensing. This proactive approach helps companies avoid patent disputes and litigation, which can be expensive and disruptive. Likewise, patent holders conduct infringement analysis to determine if a competitor’s product falls within their patent scope. Early analysis allows businesses to make informed decisions. For example, conducting a patent infringement analysis can inform a business on whether to pursue a licensing deal, or implement design modifications to avoid infringing a patent. If there is significant risk of patent infringement, it is important to seek the legal opinion of an experienced patent attorney. In short, careful analysis helps manage risk and avoid unwelcome surprises.

Direct vs. Indirect Patent Infringement

U.S. patent law recognizes several types of infringement. The most straightforward is direct infringement, which can be either literal infringement or infringement under the doctrine of equivalents. Literal infringement means the accused product or process contains every claim element exactly as stated in the patent claim. If any limitation of the claim is missing in the accused product, there is no literal infringement.

However, even if a product does not copy the claim word-for-word, a patent owner might still prove infringement under the doctrine of equivalents. This doctrine prevents an alleged infringer from escaping liability by making only insubstantial changes. The Supreme Court in Graver Tank & Co. v. Linde Air Products Co., 339 U.S. 605 (US 1950) established that a product infringes under the doctrine of equivalents if it performs substantially the same function in substantially the same way to achieve the same result as the claimed invention. The doctrine of equivalents established by Graver Tank prevents trivial alterations from undermining a patent. In other words, if the differences between the accused product and the claim are minor or insubstantial to a person skilled in the art, the product may infringe via equivalence.

A patent owner's rights may also be violated through indirect infringement, which includes two flavors: inducement and contributory infringement. A party can be liable for infringement for encouraging or assisting another in infringing a patent, which constitutes inducement. Selling components with no substantial noninfringing uses and that are only operable to be used in an infringing device or system, constitutes contributory infringement. Both forms of indirect infringement require that the defendant must have known of the patent and intentionally or recklessly encouraged infringement by a third party.

The Patent Infringement Analysis Process

Conducting an infringement analysis typically involves multiple steps, as discussed below.

Step 1: Identify Relevant Patents

Companies should conduct a patent search for existing patents in their product’s field to see if any patent holders have rights that cover similar technologies or features. This often involves reviewing patent databases (e.g., the patent office records) and prior art (earlier patents and publications) to pinpoint patents of concern.

Step 2: Claim Construction

The heart of infringement analysis is interpreting the patent claims – a process known as claim construction. One must understand each claim’s language and limitations in light of the patent’s specification and prosecution history, which is the record of proceedings in the patent office. This step should involve patent attorneys or other legal professionals, since determining the exact meaning of technical claim terms is critical.

Step 3: Comparison

Finally, the construed claims are compared to the product or process in question (often called the accused product or process). If at least one claim is met element by element by the product or equivalently met, under the doctrine of equivalents, then the product infringes that claim. The analysis must be meticulous. If the product omits or alters a key element such that it is not equivalent, the product may avoid infringement. By systematically determining which claim elements are present in the product, companies can identify potential areas of concern and gauge the likelihood of infringement.

The Role of Claim Construction

Claim construction is the interpretation of the patent claims and is a crucial aspect of any infringement case. In U.S. patent litigation, claim construction is performed by judges, not juries, typically in a pre-trial hearing called a Markman hearing. The U.S. Supreme Court in Markman v. Westview Instruments, Inc. 517 U.S. 370 (US 1996) held that “the construction of a patent, including terms of art within its claim, is exclusively within the province of the court.” This means a judge determines what the patent claims mean, and then the fact-finder (judge or jury) decides if the accused product meets those claims as construed. This case led to the now-routine Markman hearings in patent litigation, demonstrating how crucial claim interpretation is in infringement cases.

Proper claim construction relies on intrinsic evidence, the patent’s text and prosecution history, and extrinsic evidence, such as expert testimony, dictionaries, and authoritative technical references. In pre-litigation analysis, the exercise is to anticipate how a court might interpret key claim terms. Understanding claim scope is critical. A broad claim interpretation might cover your product, whereas a narrow interpretation might not. Consulting experienced patent attorneys or law firms for claim construction analysis can provide clarity on whether a competitor’s patent actually covers your product’s features. By grasping claim scope, companies can better assess potential infringement risks and consider design modifications if needed to avoid falling within the claims.

Literal Infringement vs. Doctrine of Equivalents

It is worth reiterating the difference between literal infringement and infringement under the doctrine of equivalents, as this is a common source of confusion. Literal infringement requires that the accused product or process has each and every limitation of the patent claim present exactly (word-for-word). If a claim element is missing or altered, literal infringement does not exist. However, under the doctrine of equivalents, a product may infringe if the differences from the claim are insubstantial. Courts often apply the “function-way-result” test from Graver Tank: does the accused product’s element perform substantially the same function in substantially the same way to achieve the same result as the claimed element? If yes, it may be deemed an equivalent. That said, not every change can be swept in under this doctrine.

The Supreme Court in Warner-Jenkinson Co. v. Hilton Davis Chem., 520 U.S. 17 (US 1997) emphasized an “all-elements rule”: the doctrine of equivalents is applied element by element, meaning a substitute element is only equivalent if it matches the function/way/result of the specific claim element it replaces. Additionally, prosecution history can limit the doctrine: if a patent claim was narrowed during examination (e.g., to overcome prior art), the patent owner may be estopped or barred from later claiming the surrendered range as an “equivalent”, creating prosecution history estoppel. The Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002) decision clarified prosecution history estoppel, holding that if a patentee narrowed a claim to get the patent granted, they may be barred from later claiming the narrowed-out equivalents. Festo provides a framework for when estoppel limits the doctrine of equivalents, giving more certainty to those who rely on prior art to design around patents. In practice, this means companies should look not only at the issued claims but also at the patent’s file history to see if the inventor gave up certain claim scope, which could provide leeway to design around and avoid infringement.

Avoiding Patent Infringement - Assessing and Mitigating Infringement Risks

When a potential infringement risk is identified, there are several options to mitigate it. One common step is obtaining a legal opinion, a freedom-to-operate or clearance opinion, from a patent attorney. A written opinion analyzing the patent and the product can help show that the company conducted due diligence and in good faith believed it did not infringe. This due diligence can be important if litigation arises, particularly on the issues of willful infringement and monetary damages.

If the risk is significant, a company might choose to redesign the product by altering or omitting features that are problematic. Such design modifications may result in the product no longer performing the same function in the same way as the patented invention, thereby steering clear of the claims. Another strategy is obtaining a patent license by negotiating with the patent holder for permission to use the patented technology. Licensing allows use of the invention in exchange for royalties or a fee, avoiding conflict.

Companies also often monitor competitor patents to be aware of any new patented design or technology that could pose a threat. In some cases, if a competitor’s patent is broad and potentially invalid, a company might challenge the patent’s validity through proceedings at the USPTO (e.g., a Post-Grant Review), in which patent invalidity can be challenged based on prior patent publications, prior art products, or other public information that demonstrates that the patented invention was already known. Patent validity is a key aspect of liability risk analysis. A valid patent should be licensed or designed around, whereas pursuing invalidation of a weaker patent may be the most economical approach. Each situation is unique, and various factors will influence the course of action, including the potential business impact, the strength of the patent, the ease of design around, and the relationship with the patent owner. By proactively assessing potential areas of infringement risk and taking appropriate action, businesses can reduce litigation risk and make more confident choices about their product and service offerings.

Remedies for Patent Infringement

U.S. law provides certain remedies for patent infringement. The primary categories of remedies are injunctions and damages. An injunction is a court order stopping the infringing activity, e.g., prohibiting the sale of the infringing product. However, after the Supreme Court’s decision in eBay Inc. v. MercExchange, L.L.C., 547 U.S. 388 (US 2006), injunctions in patent cases are not automatic. The patentee must satisfy the traditional four-factor equitable test by showing, among other things, irreparable harm and that monetary damages are inadequate. Courts will weigh the balance of hardships and the public interest before granting an injunction.

On the damages side, a patent owner is entitled to at least a “reasonable royalty” for the use of its invention, and potentially monetary damages for lost profits if the infringement caused lost sales. Under 35 U.S.C. § 284 enhanced damages up to treble damages (three times the amount) may be awarded to the plaintiff in the case of willful infringement. For example, if an infringer knew of the patent and deliberately copied the patented invention, they may be liable for enhanced damages. In Halo Electronics, Inc. v. Pulse Elecs., Inc., 579 U.S. 93 (US 2016), the Supreme Court clarified that district courts have discretion to award enhanced damages in cases of egregious misconduct by the infringer, making it easier to punish willful violators. Additionally, in “exceptional” cases, the court may award attorney’s fees under 35 U.S.C. § 285. These legal remedies underscore why businesses should take patent infringement analysis seriously. An infringing product or process can lead to substantial financial liability and injunctions that disrupt business.

Conclusion

Patent infringement analysis is an important exercise for any company navigating today’s technology and product landscape. The analysis allows companies to make strategic choices relating to product and service development. Patent infringement should be avoided whenever possible, as patent disputes are complicated and costly. With high stakes including monetary damages and injunctions on the line, a professional yet accessible approach to infringement analysis is indispensable. It is recommended that you consult with experienced patent attorneys when dealing with such issues. It is advisable to keep abreast of relevant patents in your field.

If you need assistance with patent issues or other intellectual property matters, contact our office for a free consultation.

© 2025 Sierra IP Law, PC. The information provided herein does not constitute legal advice, but merely conveys general information that may be beneficial to the public, and should not be viewed as a substitute for legal consultation in a particular case.