Key Takeaways

  • Patent claim construction defines how the words of a patent claim are interpreted by courts and the USPTO, forming the foundation of infringement and validity determinations.
  • Courts rely on intrinsic evidence (claims, specification, prosecution history) and, when necessary, extrinsic evidence (expert testimony, dictionaries).
  • Markman hearings are critical judicial proceedings where a judge construes patent claims before a trial begins.
  • Claim construction directly impacts both patent infringement and patent validity; even minor linguistic nuances can alter case outcomes.
  • The Phillips v. AWH Corp. decision remains the leading precedent guiding interpretation standards in the U.S.
  • Strategic drafting and consistent terminology during prosecution are key to ensuring favorable claim construction.
  • PTAB and Federal Circuit rulings show that inconsistent constructions can lead to divergent patentability outcomes.
  • Working with a patent attorney ensures claims are precise, defensible, and enforceable.

What Is a Patent Claim?

A patent claim is the part of your patent application, typically for utility patents, that explains what it is you are trying to protect. 

Patent Claim Construction: What is it?

If you have to accuse a person or company of stealing your idea, you will need to prove there has been patent infringement. This process has two steps:

  • There is the patent claim, which explains the product's use and makeup.
  • There is the infringement analysis, which determines whether or not the claim has been violated.

This means you can't determine the second part (and win the case) without having a strong claim.

In most patent courts, the judges (or the juries) are told to focus more on written evidence than physical evidence. Instead of comparing two finished products, they are asked to read the claim, determine what the creator was trying to make, and decide if the other party stole the idea. Because the key players are focused on the words, the claim's language is crucial to the court process.

Key Steps in Patent Claim Construction

Patent claim construction is a legal process in which a court interprets the meaning and scope of the terms used in a patent’s claims. The process typically begins during pre-trial proceedings, most notably through a Markman hearing, named after Markman v. Westview Instruments, Inc. (1996). In this hearing, the judge—not the jury—decides how to interpret the language of the claims.

The construction process generally involves:

  1. Examining Intrinsic Evidence – This includes the claim language itself, the patent specification, and the prosecution history before the USPTO. These sources are given the greatest weight since they reflect what the inventor actually claimed.
  2. Considering Extrinsic Evidence – When claim terms remain ambiguous, courts may look to dictionaries, expert testimony, and technical literature for guidance.
  3. Applying Contextual Meaning – Courts often interpret claim terms as they would be understood by a “person of ordinary skill in the art” (POSITA) at the time of invention, ensuring that technical terms are read in their proper scientific or industry-specific context.

Effective construction ensures consistent interpretation across infringement and validity analyses. Misinterpretation at this stage can fundamentally alter the legal protection scope of the patent.

Why is Patent Claim Construction Important?

According to Touro Law Review, the claim construction is one of the main determinants used within a case. Both legal teams will review the construction of the patent and how the owner described it to determine if the defendant is guilty of stealing an idea or design. If the claim is poorly written, then there will be plenty of holes in the case. This means that the more detail used when crafting the claim, the better.

There are three parts within a claim that companies need to keep in mind as they write it:

  • It must be written in a way that an ordinary person could understand.
  • It must cover what the inventor wanted to create and what was actually created.
  • It must prove that the claim is a valid patent from the U.S. Patent and Trademark Office.

Without any one of these parts, a court cannot determine that a patented idea was illegally taken and used for a profit.

The Role of Markman Hearings and Federal Circuit Review

A Markman hearing is the procedural focal point of patent claim construction. It allows each party to present their interpretation of the disputed terms, often supported by expert testimony and documentary evidence. The judge’s ruling establishes the definitive meaning of the claims for the remainder of the case.

Importantly, this ruling is not merely procedural—it often determines the outcome of the case. Once a claim is construed, infringement and validity are assessed under that interpretation. For instance, in Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc. (2015), the Supreme Court clarified that factual determinations underlying claim construction must be reviewed for clear error, while legal conclusions are reviewed de novo on appeal.

This division underscores how factual context—scientific meaning, industry understanding, or technology evolution—can sway the legal interpretation of claim language. Consequently, well-prepared expert testimony and clear patent drafting are essential for success during Markman proceedings.

Reasons to Consider Using a Patent Claim

Even if you don't have a patent on an item – or are considering applying for a patent – you need to keep claims in mind. According to the Patent Act, all applicants are required to include a claim in their file. This has been part of the law since 1822. By describing what it claims is its own invention, the company is able to record in writing what it made.

This history is significantly stronger in court than modern records. Almost anyone can say that they had an idea for something, but a claim filed with the original patent proves that the idea belongs to the owner.

There is also a modern reason to include a strong claim when creating a patent. "Patent Trolls" are companies that buy up patents in order to collect licensing fees by threatening lawsuits against, or actually suing companies that have developed products supposedly covered by the patent, according to the Notre Dame Law Review. Without a well-written claim, a troll can assert that a company's product or idea is infringing on its patent. TV host John Oliver even covered this concept on his show, "Last Week Tonight."

Examples of Patent Claim Construction

 In Clare v. Chrysler, in 2016, Scott Clare, Neil Long, and Innovative Truck Storage lost their case against the carmaker because they did not specifically define their claim and explain its use and purpose. They had developed hidden storage boxes for trucks that they claimed Chrysler stole. While they argued that the purpose was clear to any regular person, the court disagreed. Had they written a clear claim, the case might have been stronger.

Claims are one of the hardest parts of the process of applying for a patent. Most written pieces fall into two categories:

  • They are too narrow, which means the claim was too specific to be infringed.
  • They are too broad, which means it's impossible to claim them for their own.

For example, an appliance company could patent a specific type of washing machine. The claim would be too broad if it only said "it's a washing machine," but it would be too narrow if it explained every measurement of the machine, down to the last detail.

Claims are typically constructed from three separate parts:

  • A preamble, which identifies the type of invention.
  • A transitional phrase, (typically either "comprising" or  "consisting of," which sets up a list of criteria.
  • One or more limitations that help identify the product. 

The 2015 case Teva Pharmaceuticals USA v. Sandoz Inc. is a great example of writing claims that are too broad or too narrow. In this case, the patent claimed that a multiple sclerosis drug's "active ingredient" had a certain molecular weight. The claim did not identify how the active ingredient was determined (there are multiple ways) and how to calculate molecular weight. This means that any company could recreate the drug without breaking the law.  

Recent Developments in PTAB and Federal Circuit Decisions

Recent decisions from the Patent Trial and Appeal Board (PTAB) and the Federal Circuit highlight the evolving nature of patent claim construction. In Netflix, Inc. v. DIVX, LLC (IPR2020-00558, Feb. 2024), the PTAB showed how different interpretations of a single term can lead to opposite patentability outcomes. The Board emphasized that even slight variations in grammatical interpretation or technical terminology can be dispositive.

Another example, Blackbird Tech LLC v. ELB Electronics, Inc., illustrated the Federal Circuit’s focus on contextual claim understanding. The court sided with the defendants, holding that the patentee’s overly broad reading ignored clear specification language that limited the invention’s scope.

These cases reaffirm the Phillips standard, which prioritizes intrinsic evidence, and illustrate that consistent terminology between the specification, claims, and prosecution record is vital. They also show that claim construction is not merely academic—it defines whether a patent stands or falls.

Common Mistakes With Patent Claim Construction

The team at PatentlyO explains that patent applications should have highly technical terms explained in a way almost anyone could understand in order to help the patent office know just what the application is for. This can be done, they said, by defining terms at the beginning of the claim and explaining the products or the industry.

The rise of technology is a strong example of this. The software industry has its own challenges when it comes to patent claims because the wording involved (as well as the technology) is so new. Many terms that are common today didn't exist 20 years ago, leaving the patent office to play catch-up.

If the patent office is unable to completely understand why the claim is necessary to protect the inventor's business, it can reject the claim and let the company's competitors take its trade secrets.

Best Practices for Strong Patent Claim Drafting

To avoid pitfalls in patent claim construction, inventors and attorneys should adopt clear drafting strategies early in the patent process:

  • Define key terms in the specification – Ensure all critical terms are defined explicitly, especially those that may carry technical or industry-specific meanings.
  • Maintain consistency – Use consistent terminology across claims, descriptions, and drawings to prevent ambiguity.
  • Avoid unnecessary jargon – While precision is key, overly technical language can create interpretive confusion.
  • Anticipate potential disputes – Consider how an opposing party or the PTAB might construe each term; include clarifying examples or embodiments.
  • Align with legal precedent – Draft claims in accordance with principles from Phillips v. AWH Corp., Teva v. Sandoz, and other key cases.

In addition, understanding how the PTAB interprets terms under the “broadest reasonable interpretation” standard (for certain proceedings) versus the Phillips standard (for district courts) can shape strategic claim language decisions.

Patent applicants can benefit significantly from legal counsel experienced in claim drafting and litigation. You can find skilled patent attorneys on UpCounsel to ensure your claims are robust, defensible, and strategically constructed for both prosecution and enforcement.

Frequently Asked Questions

  1. What is the main purpose of patent claim construction?
    It determines how patent claims are interpreted in court, guiding infringement and validity analyses by defining the exact boundaries of the invention.
  2. Who decides how a patent claim is construed?
    Judges handle claim interpretation in Markman hearings, often using expert testimony and intrinsic patent documents for reference.
  3. What is the difference between intrinsic and extrinsic evidence?
    Intrinsic evidence includes the claims, specification, and prosecution history; extrinsic evidence consists of outside materials such as dictionaries or expert opinions.
  4. How does claim construction impact PTAB proceedings?
    The PTAB applies specific interpretation standards that can affect patentability. Even small differences in construction may determine whether claims are upheld or invalidated.
  5. What’s the best way to avoid claim construction disputes?
    Use clear, consistent, and well-defined claim language and seek guidance from experienced patent counsel early in the drafting process.

Companies that want to file patents should consider hiring a lawyer to write their claims. You can post your patent needs here and get free custom quotes instantly from the top 5% of lawyers on UpCounsel with an average of 14 years of experience. A professional found through UpCounsel will make sure to use the precise language needed so that a company's patents are protected for several years (and through several cases) to come.