How to Identify Patent Infringement Using Claim Charts | IIP Search

As the modern world moves towards becoming an innovation-driven one, protection of intellectual property becomes of great significance to inventors and businesses alike.

Patent infringement is the term used to describe unauthorized utilization of patented technology, which can result in monetary loss, damaged reputation, and even prolonged litigation. Among the most effective tools in detection and proving infringement is the claim chart.

This structured analytical document bridges the gap between patent claims and product features, providing clear, visual evidence of potential overlap.

In this blog, we will describe how to find patent infringement using claim charts, outline each step of the process in detail, and indicate common pitfalls, as well as show how professional Evidence of Use services can help improve your IP strategy.

Understanding Patent Infringement and Its Impact

Patent infringement is the manufacture, use, sale, or importation of an invention within the scope of another party's patent claims without authorization.

Even unintentional overlap in features can be an infringement.

For instance, if a smartphone manufacturer uses a particular antenna design that is already patented, then it may be sued for patent infringement.

The consequences are serious:

• The courts can require the infringer to pay royalties or compensation as damages.
• Injunctions: The infringing product may be banned from sale.
• Reputation risk: Litigations threaten public trust and investor confidence.

Early infringement detection aids companies in redesigning, license negotiation, or patent litigation.

Claim charts can provide a much needed orderly way of comparing product features against patented claims to uncover such risks before they escalate.

What is a patent claim chart?

An Evidence of Use or EoU chart is a detailed document showing a correspondence between each patent claim element and the corresponding features of a product or technology.

It usually consists of two parts:

1. Patent Claim Side: details every claim from the patent, broken into specific elements.
2. Product Feature Side: Describes or shows where those elements appear in the accused product, with references including technical documents, images, or schematics.

In the case of a patent that claims “a touch-sensitive display integrated with a control circuit,” for example, the chart might include screenshots or datasheets from a device showing that same integration.

Claim charts have been used in various IP contexts:

• Litigation: As evidence in infringement lawsuits.
• Licensing: To support negotiations with potential licensees.
• Due diligence: During merger, acquisition, or IP portfolio analysis.

Claim charts make complex patent analysis transparent and defensible by clearly showing which claim elements are met or not met.

Steps to Identify Patent Infringement Using Claim Charts

Patent infringement identification requires a detailed legal and technical consideration. Each step builds on the prior one to ensure accurate and defensible conclusions.

Step 1: Analyze Patent Claims

First, interpret the patent claims. These are the claims that legally define the boundary of the invention: what is protected, what is not.

Distinguish each claim in turn into its basic essentials or limitations. Consider both the independent and dependent claims.

The independent claims define the core invention to which the dependent claims add particular refinements or embodiments.

For example, a patent might claim:

• "A sensor system including a motion detector and a signal processor."
• A dependent claim might read:
• ".wherein the signal processor filters the ambient noise."

Understanding these nuances makes for correct mapping later.

Read the patent specification and drawings for context. The specification and drawings provide context in cases of ambiguous terms or technical language.

Accurate claim interpretation is the building block of each infringement analysis.

Step 2: Product Features vs. Patent Claims

Gather a wide range of information about the accused product: technical specifications, manuals, teardown reports, or marketing materials.

Then, map each claim element to the product feature that performs the same function or structure.

Ask:

• Does the product contain all of the claim elements?
• Do they have the same structure or function as the invention?

If all elements of a claim are found in the product, infringement may exist.

The claim may not apply if one element is not present or operates differently.

Example:

If a patent claims "a rechargeable lithium battery with a thermal cut-off circuit," and the product uses a similar circuit but made with a different mechanism, it may not infringe — depending on claim wording.

Precision and technical insight are key in this step.

Step 3: Document Findings in a Claim Chart

After comparison, the findings are compiled as a structured claim chart.

Use two columns, one for patent claim text and one for matching product evidence.

Each line must contain:

• The claimed element under consideration.
• The product feature corresponding to it.
• Supporting evidence such as screenshots, datasheets, or patent figures.

Add in annotations or brief explanations about how the product meets or does not meet each claim.

This documentation creates a transparent record of your analysis.

Well-developed claim charts will be compelling in negotiations, litigation, or licensing discussions.

Benefits of Utilizing Claim Charts for Infringement Analysis

Using claim charts offers several clear advantages:

1. Accuracy and Clarity: Claim charts organize complex patent wording into sections for easy comparison. Results can be interpreted without confusion by both legal and technical teams.
   
   
2. Evidence Support: They act as credible evidence in court or licensing negotiations, reflecting a clear correspondence between patent and product.
   
   
3. Risk Reduction: Early detection of infringement could lead to product modification or the negotiation of licenses before legal battles begin.
   
   
4. Improved Collaboration: Claim charts can be used as a common analytical framework for decision-making among engineers, attorneys, and business leaders.
   
   
5. IP Strategy Management: Claim charts also help identify opportunities for cross-licensing or portfolio strengthening.

In other words, claim charts create both preventative and offensive values: they prevent infringement while allowing you to enforce your own IP rights more effectively.

Common Mistakes to Avoid in Claim Chart Preparation

Even experienced analysts can make mistakes that weaken infringement assessments. Some common pitfalls include:

• Misinterpreting claim scope: Overlooking specific language or ignoring dependent claims.
• Poor documentation of a product: Lack of strong technical evidence for mapping.
• Assuming functional equivalence: When someone assumes two features are the same, but they never check that they are similar either structurally or functionally.
• Poor formatting: Poor presentation creates confusion in the courts.

To avoid these errors:

• Always cross-check claims against the specification and file history.
• Include verifiable sources, such as product datasheets or teardown images.
• Have legal and technical experts review the chart before using it.

Accurate claim charts can make or break a patent dispute or licensing negotiation.

Case Study: Claim Chart in Action

Scenario:

A manufacturer of medical devices believed that a competitor's new blood pressure monitor infringed its patented "pressure sensing algorithm."

Action Taken:

With the support of professional analysts, the company's IP team developed a claim chart that compared the key claims of the patent with the product code and marketing materials from the competitor.

Results:

The analysis indicated that the mathematical process used by the defendant to find pulse rate variability was exactly the same as the process identified in the patent claim.

Outcome:

With the claim chart in hand, the company made presentations of the evidence during the pre-litigation discussions.

The competitor would later agree to a licensing deal rather than a lawsuit, which was worth millions annually.

Lesson:

A well-documented claim chart proves infringement but also supports negotiation and value recovery without facing courtroom battles.

Real-World Example from the Tech Industry

Companies like Apple and Samsung used claim charts extensively in the early smartphone wars.

Apple's charts mapped the patent claims related to multitouch gestures and graphical interfaces to Samsung's devices.

Precise mapping of "pinch-to-zoom" and "rubber-banding" effects served as strong evidence in court. These claim charts were of central importance in defining the scope of infringement and calculating damages. 

This case exemplifies how claim charts transform abstract patent language into tangible, defensible evidence. 

Why Professional EoU and Claim Chart Services Matter 

Although it may sound like an easy undertaking, preparing a claim chart requires significant knowledge in both patent law and technology. Professional Evidence of Use and Claim Chart creation services ensure: 

• Precise Claim Interpretation: Understanding complex legal and technical terminology. 
• Accurate mapping by using trusted databases and analysis tools. 
• Litigation readiness: Produce documentation that stands up in legal review.
• Efficiency: The ability to reduce research time and deliver quality reports as fast as possible. 

At IIP Search To compare in detail, analysts rely on advanced patent databases, product documentation, and AI-assisted comparative tools. Their reports on EoU are structured, verifiable, and ready for licensing, litigation, or defensive strategy. Partnering with professionals minimizes errors, further strengthening your position in IP enforcement or negotiation. 

FAQs 

Q1. What is the difference between a claim chart and an Evidence of Use, EoU chart?

They are similar in most ways. A claim chart focuses on mapping patent claims to product features, while an EoU chart adds supporting evidence as a way of proving the use of patented technology. 

Q2. Can a claim chart prove infringement on its own? 

No. While a claim chart provides good proof, it needs supplementation through expert testimony, technical documentation, and legal interpretation in court. 

Q3. Who prepares claim charts? 

Typically, claim charts are prepared by professional patent analysts, IP attorneys, or research firms such as IIP Search using specialized databases and resources. 

Q4. How long does a claim chart analysis take? 

It could range from a few days to several weeks, especially for multi-claim or multi-product analysis, depending on the complexity. 

Q5. Are claim charts used outside of litigation? 

Yes, they are also applied in licensing negotiations, patent valuation, competitive intelligence, and due diligence during mergers or acquisitions. 

Conclusion: 

Fortify your IP strategy with claim charts. Identifying patent infringement isn't just about defending your rights - it's about securing your competitive edge. A claim chart is a clear, tabulated comparison of patent claims with product features, allowing early risk detection and confident legal or business decisions. Whether you are an inventor protecting your creation or a company evaluating competitors, claim charts turn complex analysis into actionable insight. For precision and credibility, partner with professionals who understand both the legal and technical aspects of patent research. 

Protect your innovation with IIP Search's Evidence of Use (EoU) and Claim Chart Services — Your reliable partner in the effective identification of infringement and IP enforcement success.