Key Takeaways

  • Patent infringement analysis determines whether a product or process violates the scope of a patent’s claims through literal infringement or the doctrine of equivalents.
  • The process begins with claim construction—interpreting the patent’s claims to understand their meaning and scope—followed by comparing those claims to the accused product or process.
  • Literal infringement requires every element of a claim to be present in the accused product, while infringement under the doctrine of equivalents covers minor, non-substantial differences.
  • Infringement types include direct infringement, contributory infringement, and process patent infringement, each with specific statutory definitions.
  • Effective analysis requires reviewing patent specifications, prior art, prosecution history, and potentially expert testimony to interpret technical terms.
  • Both courts and specialized tools can assist in analyzing patent data and determining infringement risk.

What Is Patent Infringement Analysis?

Patent infringement analysis involves determining if a claim of patent infringement falls under the category of literal infringement or infringement under doctrine of equivalents. Patent infringement refers to a case when another party inappropriately uses, sells, or makes a patented item without obtaining permission from the patent holder.

Types of Patent Infringement

Patent infringement can occur in several forms, each with distinct legal definitions under U.S. law:

  1. Direct Infringement – Occurs when a person or entity, without authorization, makes, uses, sells, offers to sell, or imports a patented invention within the United States during the patent term.
  2. Indirect Infringement – Includes contributory infringement and inducement:
    • Contributory Infringement: Supplying a component specifically designed for use in a patented invention, knowing it to be infringing.
    • Induced Infringement: Actively encouraging or aiding another party to infringe a patent.
  3. Process Patent Infringement – Using a patented process or importing a product made through a patented process without authorization.
  4. Willful Infringement – Deliberate disregard for a patent holder’s rights, which may lead to enhanced damages.

Courts consider the specific actions and intent of the accused party, as well as the technical scope of the claims, when determining which type of infringement applies.

What Is Literal Infringement?

Literal infringement is when the accused device is completely encompassed by the jurisdiction of the properly interpreted claims.

Usually, the specification and the drawings are more general. The examination process usually involves narrowing the claims. In some cases, there are drawings that depict a whole product but only a small aspect is claimed. The filed application may depict something that possesses many similarities with your patented product. However, at some point in the process of getting a patent, the patentee may have changed the claims to surrender coverage of your patented product.

Frequently, a patentee will interpret their patent by considering what they're selling. A product may not actually be defined by the patent's claims. Products often develop away from the issued patent's claims. Therefore, you should not make the mistake of comparing your product to the product of the patentee. You also shouldn't allow the patentee to focus on the similarities between their product and your product.

The accused device needs to violate all of the claim's limitations literally or via the doctrine of equivalents for the claim to qualify as infringement. A claim is not considered literal infringement if even a single claimed element is absent.

If a claim possesses a "means plus function" element, the following must be true for the element to be met under literal infringement:

  • The accused product possesses the function described in the element.
  • The accused product is similar in terms of material, structure, or acts delineated.

Under 35 U.S.C. §271, an individual is guilty of direct infringement if they use, make, sell, or offer to sell a patented invention in the United States without authorization during the patent's term. Importing a patented invention into the United States without proper authorization is also considered direct infringement.

Contributory infringement, under 35 U.S.C. §271, is when an individual sells a part of a manufactured, patented machine, apparatus, material, combination, or composition that constitutes a part of a patented invention. This is particularly true if the part was adapted or made for the patented invention.

Under 35 U.S.C. §271, process patent infringement is when an individual uses, sells, or offers to sell a product within the United States without authorization and the product is made by a patented process. Process patent infringement also applies to products imported into the United States without permission from the holder of the patent for the process.

Doctrine of Equivalents

When a product or process does not literally meet every element of a patent claim, it may still infringe under the doctrine of equivalents. This doctrine applies if the accused product performs substantially the same function, in substantially the same way, to achieve substantially the same result as the claimed invention.

Key points include:

  • The doctrine prevents an infringer from avoiding liability by making only insubstantial changes to a patented invention.
  • Courts may apply the function-way-result test or assess whether differences are "insubstantial" in light of the claim's purpose.
  • Prosecution history estoppel can limit application of the doctrine if claim scope was narrowed during examination to obtain patentability.

Two-Step Process

In the United States, determining infringement in court involves two major steps:

  1. Claim construction, or the determination of the claim's scope.
  2. The court rules whether the accused product infringes the patented invention.

Evidence and Tools in Infringement Analysis

An effective patent infringement analysis often relies on a combination of legal and technical evidence:

  • Patent Documents – The patent’s specification, claims, and drawings define the legal boundaries.
  • File History (Prosecution History) – Shows how the patent evolved during examination, including amendments and arguments.
  • Prior Art – Identifies whether similar inventions existed before the patent filing.
  • Technical Inspections – Reverse engineering, product testing, and design schematics can confirm whether features align with claim elements.
  • Expert Testimony – Specialists may explain how a technical feature operates relative to the claimed invention.
  • Patent Analytics Tools – Software platforms can cross-reference patent claims with technical data to identify potential overlaps or conflicts.

What Is Claim Construction?

Claim construction refers to when a court determines the meaning and scope of the claims of a patent. During the process of claim construction, terms are interpreted based on their plain or literal meaning. The only exception to this rule is if the patent holder has given a term a new, special meaning. Whether the inventor has given a term a new meaning can be determined by referring to the specification.

Under 35 U.S.C. §112, the "means plus function" form can apply to claim language. Section 112, 16 allows an element within a claim to be interpreted as a step or as a means for completing a certain function. The scope of these claims is not infinite. Rather, the scope is limited to structures described explicitly in the specification as well as corresponding equivalents. The statutory provision requires the use of the specification as a reference to prevent an excessively broad or narrow claim construction.

When it comes to claim construction, if the claim's meaning for technical terms is not clear, the court may rely on other evidence in the form of textbooks, expert witness testimony, etc. It is solely under the jurisdiction of the court to decide claim construction. The parties possess the right to have a jury trial when it comes to whether the accused product is patent infringement under the interpretation of the judge.

Defenses to Patent Infringement

Several legal defenses can be raised in response to a claim of infringement:

  1. Non-Infringement – Arguing that one or more claim elements are not present in the accused product or process.
  2. Invalidity – Challenging the patent’s validity based on lack of novelty, obviousness, inadequate disclosure, or improper subject matter.
  3. Patent Misuse – Claiming the patent holder engaged in conduct that extends the patent’s scope beyond lawful limits.
  4. Exhaustion Doctrine – Asserting that the patent holder’s rights are exhausted after an authorized sale of the patented item.
  5. Experimental Use Exception – Rarely, activities solely for experimental purposes may be exempt from infringement liability.

These defenses require careful analysis of both the patent claims and the accused technology, often supported by expert analysis and documentary evidence.

Frequently Asked Questions

1. What is the main purpose of a patent infringement analysis?

To determine if a product or process falls within the scope of a patent’s claims, either literally or under the doctrine of equivalents.

2. How does the doctrine of equivalents differ from literal infringement?

Literal infringement requires exact correspondence to every claim element, while the doctrine of equivalents covers minor variations that achieve the same function and result.

3. Can indirect infringement occur without direct infringement?

No. Indirect infringement requires that a direct infringement has occurred, even if by another party.

4. Why is prosecution history important in infringement analysis?

It can limit claim interpretation and restrict the application of the doctrine of equivalents if the patentee narrowed claims to secure the patent.

5. What defenses are available against a patent infringement claim?

Defenses include non-infringement, invalidity, patent misuse, exhaustion, and, in rare cases, experimental use.

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