Claim Construction Comes Before Infringement
A claim chart can look precise while resting on the wrong meaning of a key term. That is why U.S. infringement analysis begins with claim construction. The question is not what a word means in ordinary conversation, nor what a technical dictionary says in isolation. The question is what a person of ordinary skill in the art would understand the claim language to mean in the context of the patent.
The Federal Circuit’s en banc decision in Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005), is the modern starting point for that inquiry.
The Claims Themselves Provide Important Context
Phillips did not replace claim language with the specification. The words of the claims remain central. Surrounding words, differences among claims, and the way the same term is used elsewhere in the claim set can all illuminate meaning.
But claim terms do not exist in a vacuum. Patents are integrated legal and technical documents. A disputed term must be read as part of that whole record rather than lifted out and assigned the broadest dictionary definition that can be found.
Why the Specification Is Usually the Most Important Guide
The specification matters because it explains the invention, the technical context, and the way the applicant used particular terms. Phillips emphasized that courts appropriately rely heavily on the written description when determining claim meaning.
Two drafting choices are especially important. First, a patentee can act as its own lexicographer by clearly giving a term a special definition. Second, the specification can contain a clear disclaimer or disavowal that narrows the ordinary reach of the claim language.
Not every description of a preferred embodiment is a disclaimer. U.S. courts generally resist importing limitations from examples into the claim without a sound textual basis. The discipline is to read the specification closely enough to distinguish contextual guidance from an actual definition or scope surrender.
Definitions, repeated descriptions, statements about what the invention “requires,” and contrasts with prior art can materially affect how a claim limitation is understood.
The Prosecution History Is Part of the Intrinsic Record
The file wrapper can show how the applicant and the USPTO understood the claim during examination. Amendments, arguments, examiner interviews, and statements distinguishing prior art may all matter.
This is also where claim construction and prosecution history estoppel must be kept conceptually separate. Prosecution statements may inform the proper meaning of a claim; a narrowing amendment may additionally limit recourse to the doctrine of equivalents under cases such as Festo. Both can affect an infringement analysis, but they do different legal work.
Dictionaries and Experts Can Help—but They Come Second
Phillips permits extrinsic evidence such as technical dictionaries, treatises, and expert testimony. Such evidence can educate the court about the technology and what skilled artisans understood at the relevant time.
But extrinsic evidence is generally less significant than the intrinsic record. It was not created as part of the patent’s public record and can be selected or framed for litigation. A dictionary definition that conflicts with the patent’s own usage is therefore unlikely to control.
A Better FTO Workflow Under Phillips
When a patent looks potentially relevant, a defensible workflow is usually:
- identify the claim terms that actually drive the infringement outcome;
- read the full claim set and compare related claims;
- search the specification for definitions, repeated usage, embodiment descriptions, and possible disclaimers;
- review the prosecution history for amendments and arguments affecting those terms;
- only then use dictionaries, technical literature, or experts to resolve remaining technical context.
This sequence matters. If an FTO report begins with a dictionary and never checks the patent’s intrinsic record, the analysis can miss the very evidence a U.S. court would consider most important.
Drafting With “Phillips Thinking”
The case is equally important before a patent is filed. Core terms should be used consistently. If a nonstandard definition is necessary, it should be deliberate and clear. Examples should support the intended scope without repeatedly describing optional features as if they were universal requirements.
Statements contrasting the invention with prior art also deserve care. A sentence written to make the invention sound distinctive can later be cited as a disclaimer. The goal is not to make the specification vague. It is to make it precise without unnecessarily narrowing what the claims can fairly cover.
The Practical Takeaway
Phillips is the reason serious U.S. claim analysis cannot stop at the claim text or a dictionary. Claims, specification, and prosecution history form the public record from which scope is determined. For FTO, infringement, validity, and drafting, that intrinsic record is the first place to look.