Claim Construction: The Foundation of Patent Disputes

When we analyse patent disputes, one principle becomes immediately clear: claim construction often determines the entire trajectory of litigation. As technical experts who regularly support claim construction arguments, we've witnessed firsthand how a court's interpretation of claim terms can make or break a case worth millions of pounds.12 This critical process—where courts define the precise meaning of patent claim language—serves as the foundation upon which all subsequent infringement and validity analyses rest.3

Empirical research validates this outcome-determinative characterisation. Studies examining all substantive decisions in patent cases filed in 2008–2009 confirm significant continuity in patent litigation outcomes over twenty years, with claim construction serving as the pivotal determinant.4 Analysis of 211 district court claim construction decisions from 2009, examining 1,858 disputed claim terms, demonstrates that claim construction fundamentally shapes patentee success rates.5 The US Federal Circuit's 75% affirmation rate of lower court claim interpretations further underscores the strategic importance of trial court claim construction outcomes.6

Claim construction represents the intersection of law and technology, requiring judges to parse complex technical language while adhering to established legal principles.7 Whether you're enforcing patents, defending against infringement claims, or evaluating patent portfolios, understanding how courts interpret claim language is essential for sound strategic decision-making.

Important: This article provides general information about patent claim construction for educational purposes. It is not legal advice and should not be relied upon as such. Patent litigation involves complex legal and technical considerations that require qualified legal counsel. Always consult a solicitor, patent attorney, or intellectual property lawyer before taking action based on claim construction analysis.

What Is Claim Construction?

Patent claim construction is the judicial interpretation of claim terms that define the scope and boundaries of patent rights.89 Claims themselves are typically complex, run-on sentences at the end of a patent document that describe what an invention covers. Understanding claim scope proves vital because parties infringe patents by making, selling, using, or offering to sell inventions as described by the claims.10

The process involves judges—not juries—determining what patent claims mean. In the United States, this principle was established in the landmark 1996 Supreme Court case Markman v. Westview Instruments.11 This unanimous Supreme Court decision, authored by Justice Souter, applied a historical test to resolve the constitutional question under the Seventh Amendment.1213 The Court found no direct antecedent of modern claim construction in historical sources, but determined that the closest 18th-century analogue—construction of patent specifications—was handled by judges, not juries.1415

The decision emphasised "functional considerations" in assigning patent claim construction to judges rather than juries, reasoning that lay juries lack expertise to interpret technical patent terminology and that judicial interpretation promotes uniformity in patent law.1617

Why Interpretation Varies

Claim interpretation varies because patent language often contains terms of art that may have different meanings to different audiences.18 A term like "inventory" could mean physical goods to one person and financial records to another, as illustrated in the Markman case itself.19 The specification may define terms explicitly, or their meaning may depend on how a person of ordinary skill in the art (POSITA) would understand them at the time of invention.2021

Additionally, patent prosecution history may reveal how claim terms were amended or argued before the patent office, potentially limiting their scope through prosecution history estoppel.2223 These multiple sources of meaning create inherent interpretive challenges that require careful judicial analysis.

Decision Framework: Approaching Claim Construction

Before engaging with claim construction issues—whether as a patent holder, accused infringer, or technical expert—work through this systematic assessment:

Step 1: Identify the Key Disputed Terms

Questions to ask:

• Which claim terms are genuinely ambiguous or contested?
• Do the parties propose materially different constructions?
• Would either construction be outcome-determinative for infringement or validity?
• Are there terms of art that require technical expertise to interpret?

Step 2: Gather Intrinsic Evidence

Essential sources (in order of priority):

1. ✅ Claim language itself—the starting point for all construction
2. ✅ Patent specification—"the single best guide to claim meaning"
3. ✅ Prosecution history—amendments and arguments before the patent office
4. ✅ Other claims in the same patent—for consistent interpretation

Step 3: Consider Extrinsic Evidence (If Needed)

Secondary sources (use with caution):

• ⚠️ Technical dictionaries—general definitions, but not controlling
• ⚠️ Expert testimony—helpful for technical context, not legal conclusions
• ⚠️ Prior art references—showing how terms were used in the field
• ⚠️ Inventor testimony—rarely persuasive, often excluded

Step 4: Assess Jurisdictional Approach

UK courts: Apply purposive construction under Catnic/Improver principles US courts: Follow Phillips hierarchy with emphasis on intrinsic evidence EPO/UPC: Consider Article 69 EPC and its Protocol on interpretation

Step 5: Evaluate Strategic Implications

For patent holders:

• Broad construction aids infringement arguments but risks validity challenges
• Narrow construction protects validity but may allow design-arounds

For accused infringers:

• Narrow construction supports non-infringement
• Broad construction may enable stronger invalidity arguments

Sources for Construction: The Phillips Hierarchy (US)

The 2005 Federal Circuit en banc decision in Phillips v. AWH Corp. established a clear hierarchy for claim construction evidence that forms the foundation of US claim construction methodology.2425 This landmark en banc ruling fundamentally reshaped patent claim construction by rejecting the approach established in Texas Digital Systems v. Telegenix (2002), which had emphasised dictionary definitions while downplaying the specification's role.2627

The Court grounded its approach in 35 U.S.C. § 112, interpreting the statute's requirement that inventors provide a "full" and "exact" description to mean that the specification "necessarily informs the proper construction of the claims."[28]

Intrinsic Evidence

Primary Sources: The plain language of the claims themselves, interpreted by a person of ordinary skill in the art, forms the foundation of any construction analysis.29 The patent specification ranks as "always highly relevant" and "usually dispositive" as "the single best guide to the meaning of a disputed term."[30]31

The prosecution history and file wrapper, though viewed with more scepticism than claim language itself, provide crucial context about how terms were presented to and considered by the USPTO.32 When intrinsic evidence alone resolves ambiguity in a claim term, relying on extrinsic evidence is improper.33

Extrinsic Evidence

Secondary Sources: Extrinsic evidence includes technical dictionaries, scholarly articles, and expert testimony.34 While permissible "in the court's sound discretion," extrinsic evidence is considered "less significant" than intrinsic sources.35 The Phillips court emphasised that dictionaries should not be given weight equal to claim language itself, rejecting the previous "dictionary-first" approach.36

Hierarchy Application

When interpreting claims, US courts apply a hierarchical approach using intrinsic evidence first—the claims themselves, specification, and prosecution history.37 Only if meaning remains unclear after consulting intrinsic sources may courts consider extrinsic evidence, including dictionaries, prior art, and expert testimony.38

Markman Hearings in the United States

A Markman hearing represents the formal proceeding where trial courts conduct claim construction in patent litigation.39 Named after the seminal Markman v. Westview Instruments decision, these hearings occur early in litigation, typically before discovery closes and summary judgment motions are filed.40

The Hearing Process

District courts exercise considerable discretion over whether, when, and how to conduct Markman hearings.41 Some courts prefer attorney argument based solely on written records, while others conduct multiday minitrials with live witnesses.42 The Northern District of California has comprehensive Patent Local Rules governing claim construction procedures, including requirements that parties exchange proposed terms for construction with preliminary claim constructions, file joint claim construction statements designating disputed terms, and limit constructions to generally no more than 10 terms.4344

The court provides approximately 90 minutes per side for argument, may schedule technology tutorials with about 30 minutes per side (with the patentee presenting first), and requires opening briefs at least six weeks before the hearing.4546

During hearings, judges use progressively broader context only when claim terms prove ambiguous, following this established order: (1) plain meaning within the claims themselves; (2) the patent specification; (3) USPTO examination records; and (4) extrinsic evidence such as expert testimony if ambiguity remains.4748

Expert Witness Role at Markman Hearings

Courts may or may not permit expert testimony at Markman hearings, and even when allowed, expert opinions on claim interpretation may receive little or no weight.49 Some courts have permitted experts to present technical "tutorials" without cross-examination or have appointed their own technical experts.50 The Supreme Court characterises expert witness input as "subsidiary fact-finding" to help judges understand technical terms.51

Importantly, expert testimony cannot transform legal analysis into factual matters—how a person of ordinary skill in the art understands claim terms considering the specification, prosecution history, and internal patent coherence remains a legal issue.52

UK Claim Construction: Purposive Approach

English courts apply purposive construction to patent claims, representing a fundamentally different approach from US methodology.53 This approach, established in the landmark 1980 House of Lords decision in Catnic Components Ltd v Hill & Smith Ltd, focuses on the "pith and marrow" of claims as understood by persons skilled in the art rather than purely literal interpretation.5455

Lord Diplock held that patent specifications should receive purposive rather than purely literal interpretation, asking whether skilled practitioners would understand that strict compliance with descriptive words was essential, or whether minor variants having no material effect should be included within claim scope.56

Legal Framework

Under Section 125 of the Patents Act 1977, the invention is "that specified in a claim of the specification of the application or patent, as interpreted by the description and any drawings contained in that specification."[57] English courts apply the Protocol on the Interpretation of Article 69 EPC, which establishes a middle ground between strict literal meaning and overly broad protection.58

The Improver Questions Framework

The Court of Appeal refined the purposive construction approach in Improver v Remington (1990), establishing three structured questions for determining whether a variant falls within a claim:59

1. Material effect: Does the variant materially affect how the invention works? If yes, it falls outside the claim.
2. Obviousness: Would it have been obvious at publication to a skilled reader that the variant had no material effect? If no, the variant is excluded.
3. Intent: Would a skilled reader understand that strict compliance was essential? If yes, the variant is outside the claim.

Key Interpretive Principles

UK courts apply well-established propositions when construing claims:60

• Claims must be interpreted through the eyes of the skilled person in the art
• Interpretation must account for the skilled person's common general knowledge
• Claims must be read in context with the specification, description, and drawings
• Construction must be purposive, having regard to the inventor's disclosed purpose
• The specification may disclose more than is claimed

Recent case law confirms that claim construction should be based on "a mind willing to objectively construe a claim" rather than the applicant's alleged intention, protecting third parties and the public.61 The purposive construction doctrine aligns with the Protocol on Interpretation of Article 69 EPC and aims to grant patentees "the full extent, but not more than the full extent, of the monopoly which a reasonable person skilled in the art would think he was intending to claim."[62]

Post-2017 Development: Actavis v Eli Lilly

In 2017, the UK Supreme Court in Actavis UK Ltd v Eli Lilly & Co held that even products or processes falling outside normal claim interpretation could infringe if variations were immaterial.63 Lord Neuberger reformulated the Improver questions and held that infringement must be assessed in two stages: (1) does the alleged infringement fall within the claim on its normal construction? and (2) if not, does it nevertheless infringe because the variant is immaterial?64

This represents a significant evolution in UK law that brings purposive construction closer to the US doctrine of equivalents in certain circumstances, though important differences remain.

UK vs US Claim Construction: Key Differences

Aspect	United Kingdom	United States
Foundational Case	Catnic Components v Hill & Smith (1980)	Markman v. Westview Instruments (1996)
Core Methodology	Purposive construction	Phillips hierarchy
Primary Focus	What skilled person would understand as essential	Plain meaning informed by specification
Variants/Equivalents	Improver/Actavis questions	Doctrine of equivalents
Expert Evidence	Technical evidence common	"Subsidiary fact-finding" only
Formal Hearing	Part of trial or CMC	Standalone Markman hearing
Appeal Standard	De novo review	Teva: mixed question approach
International Alignment	EPC Protocol on Article 69	US-specific approach

Technical Expert Role in Claim Construction

As technical experts regularly involved in claim construction proceedings, we understand the nuanced role experts play in helping courts interpret complex patent language.6566 Our contribution centres on providing the technical perspective of a person of ordinary skill in the art rather than offering legal conclusions about claim meaning.

Person of Ordinary Skill Perspective

A "person of ordinary skill in the art" (POSITA) represents a hypothetical person presumed to have known the relevant prior art at the time of invention.67 Courts and the Patent Trial and Appeal Board must clearly establish who qualifies as a POSITA before relying on expert testimony about what the POSITA would know or understand.68

Importantly, the Federal Circuit's 2024 decision in Osseo Imaging, LLC v. Planmeca USA Inc. clarified that experts need not have possessed requisite skill "at the time of the alleged invention"—experts who acquire qualifications after the invention can develop an understanding of what a POSITA knew at the relevant time.6970 The court held that "an expert can acquire the necessary skill level later and develop an understanding of what a person of ordinary skill in the art knew at the time of the invention," with "nothing more required."[71]72 This ruling broadens the potential expert witness pool and precludes arguments requiring pre-invention qualification.73

Supporting Construction Arguments

We support claim construction arguments by:

• Providing Technical Context: Explaining how terms of art are understood in the relevant field
• Educational Tutorials: Presenting technical background to help judges understand complex technology
• Prior Art Analysis: Demonstrating how claim terms relate to existing technology and publications
• Specification Review: Identifying technical disclosures that inform claim meaning
• Prosecution History Review: Explaining technical significance of claim amendments

Expert Reports and Testimony

Our expert reports typically address technical background, relevant prior art, and how a person of ordinary skill would understand disputed terms based on intrinsic evidence.74 However, we cannot offer legal conclusions about ultimate claim construction—that determination remains exclusively with the court.75

What NOT to Do: Critical Mistakes in Claim Construction

These common errors can undermine claim construction arguments. We've seen each of these mistakes affect case outcomes:

1. Importing Limitations from the Specification

The mistake: Arguing that claim terms should be limited to specific embodiments described in the specification.

Why it fails: While the specification informs claim meaning, claims are not limited to disclosed embodiments unless the patentee clearly disavowed broader scope. Phillips expressly warns against importing limitations from preferred embodiments into claims.76

Real consequence: Courts reject proposed constructions that improperly narrow claims based on specification examples, and credibility suffers when this argument is made without proper support.

2. Relying Primarily on Dictionary Definitions

The mistake: Leading with dictionary definitions rather than intrinsic evidence.

Why it fails: Phillips explicitly rejected the "dictionary-first" approach of Texas Digital. Dictionaries provide general definitions that may not reflect how terms are used in the specific patent context.77

Real consequence: Courts give little weight to dictionary definitions that conflict with intrinsic evidence, and the opposing party will highlight this methodological error.

3. Conflating Infringement and Claim Construction

The mistake: Arguing for a claim construction specifically designed to capture (or avoid) the accused product.

Why it fails: Claim construction is an exercise in understanding what the patentee meant, not in tailoring claim scope to litigation outcomes. Courts recognise result-oriented constructions and view them sceptically.78

Real consequence: Credibility damage when courts perceive that proposed constructions are litigation-driven rather than text-driven.

4. Ignoring Prosecution History

The mistake: Failing to review file wrapper contents for claim amendments and examiner arguments.

Why it fails: Prosecution history estoppel can dramatically limit claim scope. Statements made to distinguish prior art or overcome rejections may be binding on claim interpretation.79

Real consequence: Embarrassing revelations when opposing counsel produces prosecution history showing the patentee argued for a narrow construction to obtain allowance.

5. Using Experts for Legal Conclusions

The mistake: Having technical experts opine on ultimate claim construction rather than technical facts.

Why it fails: Claim construction is a matter of law for the court. Expert testimony is "subsidiary fact-finding" only—experts can explain technical terms but cannot tell courts what claims mean as a legal matter.80

Real consequence: Expert opinions struck or given no weight, wasting expert fees and potentially damaging the expert's credibility for other aspects of the case.

6. Overlooking Claim Differentiation

The mistake: Proposing a construction that renders another claim superfluous or redundant.

Why it fails: Courts apply the doctrine of claim differentiation—each claim is presumed to have independent meaning. A construction that makes one claim encompass another is disfavoured.81

Real consequence: Court adopts opposing party's construction to preserve meaning of all claims.

7. Underestimating UK/US Jurisdictional Differences

The mistake: Applying US Phillips analysis to UK proceedings or vice versa.

Why it fails: UK purposive construction and US Phillips methodology differ fundamentally. The Actavis expansion of UK equivalents doctrine and the Catnic/Improver framework have no direct US analogues.82

Real consequence: Arguments that would succeed in one jurisdiction fail in another, wasting resources and damaging credibility with the court.

Strategic Impact of Claim Construction

The strategic impact of claim construction extends far beyond the hearing itself, influencing every subsequent aspect of patent litigation from infringement analysis to settlement negotiations.8384

Impact on Infringement Analysis

Once claims are construed, infringement analysis becomes largely mechanical—comparing the accused product or process to the construed claim elements.85 Narrow claim constructions typically favour accused infringers by creating gaps between patent scope and accused products. Broad constructions favour patent owners by encompassing more potential infringement scenarios.86

The doctrine of equivalents may still apply after claim construction, but prosecution history estoppel can limit this doctrine based on amendments made during patent prosecution.8788 The Supreme Court's decision in Festo Corp. v. Shoketsu established that estoppel operates as a flexible bar rather than absolute prohibition, requiring individualised analysis.8990

Impact on Validity Analysis

Claim construction directly affects validity analysis because broader constructions increase the likelihood that prior art anticipates or renders obvious the claimed invention.91 When we analyse validity, we must apply the construed claim language to prior art references, making construction outcomes determinative of validity conclusions.92

The relationship between claim scope and validity creates strategic tensions—patent owners want broad constructions for infringement purposes but narrow constructions for validity purposes.93 This fundamental tension makes claim construction the critical battleground in most patent disputes.

Settlement Implications

Understanding the assigned judge's tendencies and optimising term selection early can significantly influence settlement positioning.94 Claim construction often functions as a summary judgment proceeding that largely predetermines litigation outcomes, making post-construction settlement negotiations critical.95

Studies show that most patent cases settle after claim construction rather than proceeding to trial, underscoring how outcome-determinative these hearings prove in practice.96 Effective settlement strategy requires anticipating likely construction outcomes and their downstream effects on both infringement and validity analyses.97

Costs & Practical Realities

Understanding claim construction requires knowing what's actually at stake financially and strategically:

UK Costs

IPEC (Intellectual Property Enterprise Court):

• Costs capped at £60,000 (liability phase) + £30,000 (inquiry as to damages)
• Total maximum adverse costs: £90,000
• Timeline: 8–15 months typical for liability determination
• Claim construction typically addressed at trial, not separate hearing

Patents Court:

• No cost caps apply
• Typical costs for full trial including construction issues: £200,000–£500,000+ per side
• Adverse costs exposure if you lose: £150,000–£400,000
• Timeline: 12–18 months to trial
• Technical expert evidence common for construction issues

Technical Expert Costs (UK):

• Claim construction analysis and report: £15,000–£40,000
• Attendance at trial for cross-examination: £3,000–£8,000 per day
• Technical tutorials: £8,000–£20,000

US Costs

Markman Hearing Preparation:

• Claim construction briefing: $150,000–$400,000
• Expert witness fees: $50,000–$150,000
• Technology tutorials: $30,000–$75,000
• Total Markman preparation: $250,000–$600,000

Full Litigation Through Markman:

• Filing through Markman: $500,000–$1,500,000+
• If case settles post-Markman: savings of $1,000,000+ vs. trial

Federal Circuit Appeal:

• Appeal of claim construction: $150,000–$300,000
• Reversal rate: approximately 25% of constructions appealed

Timeline Considerations

UK Patents Court:

• Case management conference: 2–4 months from filing
• Expert reports on construction: 6–10 months
• Trial: 12–18 months from filing
• Construction issues resolved at trial

US District Court:

• Initial disclosures: 2–3 months
• Claim construction briefing: 6–12 months
• Markman hearing: 9–15 months from filing
• Trial (if case continues): 18–36 months from filing

Strategic Calculation

The economics favour early investment:

• Thorough construction analysis before litigation: £10,000–£25,000 / $15,000–$40,000
• Rushed analysis during litigation: 2–3x higher costs, worse outcomes
• Settlement leverage from favourable construction: potentially £millions saved

Claim Construction Checklist

Use this checklist when preparing claim construction positions:

Pre-Litigation Analysis

• Identified all potentially disputed claim terms
• Reviewed full patent specification for term definitions
• Analysed prosecution history for amendments and arguments
• Considered how POSITA would understand each term
• Evaluated competing reasonable constructions
• Assessed construction impact on infringement and validity

Evidence Gathering

• Compiled relevant specification passages
• Documented prosecution history statements
• Identified technical dictionaries and treatises
• Engaged technical expert for POSITA perspective
• Reviewed prior art for consistent term usage
• Analysed other patents in same family

Jurisdictional Considerations

• Confirmed applicable legal standard (Phillips/Catnic/EPC)
• Reviewed local patent rules and procedures
• Researched assigned judge's claim construction history
• Coordinated positions across parallel proceedings
• Considered appeal standards and likelihood

Expert Preparation

• Defined POSITA qualifications clearly
• Prepared technical background tutorial
• Documented expert's methodology and reasoning
• Ensured expert avoids legal conclusions
• Prepared expert for cross-examination

Conclusion

Patent claim construction serves as the foundation upon which all patent disputes rest, making technical expert input on claim meaning critical to litigation strategy. The interplay between legal principles established in Markman, Phillips, and Catnic and technical understanding provided by domain experts creates a unique collaborative process between law and technology.9899

Key Takeaways

The fundamental principles:

• Claim construction is a question of law for the court, not a factual determination
• Intrinsic evidence (claims, specification, prosecution history) controls over extrinsic sources
• The POSITA perspective—not the inventor's or litigator's—governs interpretation
• UK purposive construction and US Phillips methodology differ significantly
• Construction outcomes often determine case outcomes before trial

Immediate priorities when facing construction issues:

1. Identify genuinely disputed terms early—don't fight over uncontested language
2. Build your construction from intrinsic evidence first
3. Review prosecution history thoroughly for estoppel risks
4. Engage technical experts for POSITA perspective, not legal conclusions
5. Consider strategic implications of both broad and narrow constructions

Critical mistakes to avoid:

• Importing limitations from specification embodiments without clear disavowal
• Leading with dictionary definitions over patent-specific evidence
• Using experts to offer legal conclusions on claim meaning
• Ignoring prosecution history until opposing counsel raises it
• Applying wrong jurisdictional approach in UK vs US proceedings

As the patent landscape continues evolving, particularly with complex technologies like artificial intelligence and biotechnology, the role of technical experts in claim construction will only grow in importance.100 Our ability to bridge the gap between legal requirements and technical reality ensures that courts can make informed decisions that properly balance patent protection with public interests.101

If you're facing claim construction issues and need technical expert support, we can help. Our technical analysis services support your legal team with POSITA analysis, specification review, prosecution history analysis, and expert testimony. We work alongside your solicitors and barristers—providing the technical foundation they need while they handle the legal strategy.

This article is for informational purposes only and does not constitute legal advice. Consult qualified legal counsel before taking any action in patent proceedings.

Contact us to discuss how our technical analysis can support your claim construction arguments.

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Sources

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[19] Markman v. Westview Instruments, Inc., case facts regarding "inventory" term interpretation.

[20] MPEP § 2111: Claim Interpretation; Broadest Reasonable Interpretation. Available at: https://www.uspto.gov/web/offices/pac/mpep/s2111.html

[21] Person of Ordinary Skill in the Art standards, MPEP § 2141.03. Available at: https://www.uspto.gov/

[22] Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722 (2002). Available at: https://supreme.justia.com/cases/federal/us/535/722/

[23] Warner-Jenkinson Co., Inc. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997). Available at: https://supreme.justia.com/cases/federal/us/520/17/

[24] Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005) (en banc). Available at: https://www.courtlistener.com/opinion/781081/phillips-v-awh-corp/

[25] Phillips v. AWH Corp., Wikipedia (2005). Available at: https://en.wikipedia.org/wiki/Phillips_v._AWH_Corp.

[26] Texas Digital Systems, Inc. v. Telegenix, Inc., 308 F.3d 1193 (Fed. Cir. 2002), overruled by Phillips.

[27] The Federal Circuit's Long-Awaited En Banc Decision in Phillips v. AWH Corp., Mondaq (2005). Available at: https://www.mondaq.com/

[28] Phillips v. AWH Corp., 415 F.3d at 1315 (discussing 35 U.S.C. § 112).

[29] Phillips v. AWH Corp., 415 F.3d at 1312–13 (claims as primary source).

[30] Phillips v. AWH Corp., 415 F.3d at 1315 ("the specification is always highly relevant").

[31] Phillips v. AWH Corp., 415 F.3d at 1315 ("usually dispositive" and "single best guide").

[32] Phillips v. AWH Corp., 415 F.3d at 1317 (prosecution history as intrinsic evidence).

[33] Vitronics Corp. v. Conceptronic, Inc., 90 F.3d 1576, 1583 (Fed. Cir. 1996).

[34] Phillips v. AWH Corp., 415 F.3d at 1318 (extrinsic evidence categories).

[35] Phillips v. AWH Corp., 415 F.3d at 1318 ("less significant than the intrinsic record").

[36] Federal Circuit Abandons 'Dictionary-First' Rule of Claim Construction, Mondaq (2005). Available at: https://www.mondaq.com/

[37] Ordinary Meaning and Plain Meaning, Virginia Law Review (2026). Available at: https://www.virginialawreview.org/

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[41] Patent Claim Construction: Understanding Markman Hearings and Litigation Strategy, Mondaq (2026). Available at: https://www.mondaq.com/

[42] Using an Expert at a Markman Hearing: Practical and Tactical Considerations, Finnegan (2026).

[43] Patent Local Rules, U.S. District Court for the Northern District of California. Available at: https://www.cand.uscourts.gov/

[44] N.D. Cal. Patent Local Rule 4-1 et seq.

[45] N.D. Cal. Patent Local Rules, claim construction hearing procedures.

[46] Patent Claim Construction: Understanding Markman Hearings and Litigation Strategy, Caldwell Law (2026).

[47] Claim construction hierarchy in practice, Federal Circuit jurisprudence.

[48] Patent Claim Construction: Understanding Markman Hearings and Litigation Strategy, Mondaq (2026).

[49] Using an Expert at a Markman Hearing: Practical and Tactical Considerations, Finnegan (2026).

[50] Technical tutorials at Markman hearings, court discretion.

[51] Markman v. Westview Instruments, Inc., 517 U.S. at 389–90 ("subsidiary factfinding").

[52] Teva Pharmaceuticals USA, Inc. v. Sandoz, Inc., 574 U.S. 318 (2015). Available at: https://supreme.justia.com/cases/federal/us/574/318/

[53] An International Guide to Patent Case Management for Judges, WIPO (2026). Available at: https://www.wipo.int/patent-judicial-guide/

[54] Catnic Components Ltd v Hill & Smith Ltd 1982 RPC 183 (HL). Available at: https://www.bailii.org/

[55] Ensygnia IP Ltd v Shell Oil Products Ltd & Ors 2023 EWHC 1495 (Pat). Available at: https://www.bailii.org/

[56] Lord Diplock's judgment in Catnic, purposive construction principles.

[57] Patents Act 1977, Section 125. Available at: https://www.legislation.gov.uk/ukpga/1977/37/section/125

[58] Protocol on the Interpretation of Article 69 EPC. Available at: https://www.epo.org/

[59] Improver Corporation v Remington Consumer Products Ltd 1990 FSR 181 (Pat Ct).

[60] General principles of claim construction, EPO Case Law (2025). Available at: https://www.epo.org/en/legal/case-law

[61] Sycurio Ltd v PCI Pal Ltd 2022 EWHC 2722 (Pat). Available at: https://www.bailii.org/

[62] Virgin Atlantic Airways Ltd v Premium Aircraft Interiors UK Ltd 2009 EWCA Civ 1062.

[63] Actavis UK Ltd v Eli Lilly & Co 2017 UKSC 48. Available at: https://www.supremecourt.uk/cases/uksc-2016-0002.html

[64] Lord Neuberger's judgment in Actavis, reformulated questions.

[65] Using an Expert at a Markman Hearing: Practical and Tactical Considerations, Finnegan (2026).

[66] The Federal Circuit Clarifies Who Can Be an Expert in Patent Cases, FBM (2026). Available at: https://www.fbm.com/

[67] Person having ordinary skill in the art, Wikipedia (2026). Available at: https://en.wikipedia.org/

[68] Construing Unambiguous Claim Language and Qualifying Challenged Expert as POSITA, JD Supra (2026). Available at: https://www.jdsupra.com/

[69] Osseo Imaging, LLC v. Planmeca USA Inc., Fed. Cir. (2024). Available at: https://cafc.uscourts.gov/

[70] Back to the Future: Expert Can Be Skilled Artisan Based on Later-Acquired Knowledge, IP Update (2024). Available at: https://www.ipupdate.com/

[71] Federal Circuit Rejects Timing Requirement for Expert Qualification Under Kyocera, JD Supra (2026). Available at: https://www.jdsupra.com/

[72] Osseo Imaging, LLC v. Planmeca USA Inc., holding on expert qualification.

[73] An Expert Witness Need Not Have Been a POSITA at the Time of the Invention, Knobbe Martens (2024). Available at: https://www.knobbe.com/

[74] Using an Expert at a Markman Hearing: Practical and Tactical Considerations, Finnegan (2026).

[75] Issue of Indefiniteness Was Reviewed De Novo, McKool Smith (2026). Available at: https://www.mckoolsmith.com/

[76] Phillips v. AWH Corp., 415 F.3d at 1323 (warning against importing limitations).

[77] Phillips v. AWH Corp., 415 F.3d at 1320–21 (rejecting dictionary-first approach).

[78] Result-oriented claim construction, judicial scepticism.

[79] Prosecution history estoppel, Festo Corp. v. Shoketsu, 535 U.S. 722 (2002).

[80] Markman v. Westview Instruments, 517 U.S. at 389–90 (expert role as subsidiary).

[81] Claim differentiation doctrine, Phillips v. AWH Corp., 415 F.3d at 1314–15.

[82] UK-US jurisdictional differences in claim construction methodology.

[83] Patent Litigation Claim Construction Toolkit, Practical Law, Westlaw (2026).

[84] Patent Claim Construction: Understanding Markman Hearings and Litigation Strategy, Mondaq (2026).

[85] Patent Litigation Part Three: An Introduction to Patent Claims, DisputeSoft (2026).

[86] A Deep Dive into Patent Claim Construction, PatentPC (2026).

[87] Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S. 722, Cornell Law (2002). Available at: https://www.law.cornell.edu/

[88] Patent Law – Infringement – Doctrine of Equivalents – Prosecution History Estoppel, Duquesne Law Review (2026).

[89] Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Justia (2002). Available at: https://supreme.justia.com/

[90] Rethinking Prosecution History Estoppel, University of Chicago Law Review (2026). Available at: https://lawreview.uchicago.edu/

[91] An International Guide to Patent Case Management for Judges, WIPO (2026).

[92] Patent Claim Construction: Understanding Markman Hearings and Litigation Strategy, Mondaq (2026).

[93] A Deep Dive into Patent Claim Construction, PatentPC (2026).

[94] Know Your Judge Before Constructing a Claim in Patent Litigation, Bloomberg Law (2026). Available at: https://www.bloomberglaw.com/

[95] Patent Claim Construction: Understanding Markman Hearings and Litigation Strategy, Mondaq (2026).

[96] What Reversals and Close Cases Reveal About Claim Construction: The Sequel, UIC Law Review (2014). Available at: https://repository.law.uic.edu/

[97] Patent Litigation Claim Construction Toolkit, Practical Law, Westlaw (2026).

[98] Markman v. Westview Instruments, Inc., 517 U.S. 370 (1996).

[99] Phillips v. AWH Corp., 415 F.3d 1303 (Fed. Cir. 2005).

[100] AI and biotechnology patent claim construction challenges, emerging case law.

[101] Samsung Electronics Co., Ltd. v. Power2B, Inc., Federal Circuit (2025). Available at: https://cafc.uscourts.gov/