Patent Claim Construction After Teva Pharmaceuticals
## Claim construction remains a legal question
Patent claims define the scope of the asserted right. Courts interpret disputed terms from the perspective of a person of ordinary skill in the art at the relevant time, reading the claims in the context of the specification and prosecution history.
Before *Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc.*, Federal Circuit review of claim construction was commonly described as entirely de novo. The Supreme Court refined that framework by distinguishing the ultimate legal interpretation from subsidiary factual findings.
## De novo and clear-error review
Under *Teva*, the ultimate construction of a patent claim remains a legal conclusion reviewed **de novo** on appeal. But when a district court resolves a genuine factual dispute concerning extrinsic evidence, Federal Rule of Civil Procedure 52(a)(6) applies, and that subsidiary finding is reviewed for **clear error**.
For example, experts may disagree about what a technical phrase meant to skilled artisans at the relevant time. If the district judge evaluates that testimony and finds one explanation more persuasive, the finding may receive deferential review. The court must still determine, as a legal matter, how that understanding affects the claim in light of the patent record.
When construction rests solely on intrinsic evidence, appellate review remains de novo. Parties seeking deference should therefore identify the specific factual dispute, develop admissible evidence, and request explicit findings.
## Intrinsic evidence comes first
The primary sources are:
- The claim language; - Other claims in the patent; - The specification; and - The prosecution history.
Claim terms generally receive their ordinary and customary meaning to a skilled artisan unless the patentee acted as a lexicographer or clearly disavowed scope. The specification is usually the best guide, but courts must avoid importing limitations from preferred embodiments into broader claim language.
The prosecution history can reveal disclaimer, amendment-based distinctions, or the applicant’s understanding of terminology. Because it records negotiation rather than polished drafting, it may be less clear than the specification.
## The role of extrinsic evidence
Dictionaries, treatises, inventor testimony, and expert opinions can illuminate technology and usage. They cannot override an unambiguous intrinsic record or rewrite the patent. Expert opinions that merely offer legal conclusions or conflict with the specification carry limited weight.
Effective expert evidence explains what background knowledge a skilled artisan possessed, why terminology had a particular technical meaning, and how competing readings affect the disclosed invention. The evidence should address the relevant priority period rather than modern usage.
## Claim differentiation
The **claim differentiation doctrine** presumes that different claims have different scope. When a dependent claim adds a limitation, that may suggest the independent claim does not already contain the same limitation.
The doctrine is a guide, not an absolute rule. It cannot broaden claims beyond a clear definition, overcome unmistakable disclaimer, or contradict the specification and prosecution record. Its force depends on the relationship among the claims and the proposed construction.
## Litigation strategy after Teva
Parties should frame claim-construction disputes early, separate factual propositions from legal arguments, and build a record suitable for review. Proposed constructions should resolve a real dispute rather than substitute one ambiguous phrase for another.
District courts can strengthen the record by identifying intrinsic reasoning, expressly resolving material factual disputes, and explaining how those findings inform the ultimate construction. Litigants should preserve objections to both the evidentiary rulings and legal conclusion.
*By Marcus Rivera, Esq. This article provides general information, not legal advice.*