Claim Construction Toolkit: Terms, the Record, and Markman Strategy

By Casey Scott McKay · 2026-06-29

Claim construction decides more patent cases than any other event, and it is decided almost entirely on documents written years earlier by people who were not thinking about litigation. This toolkit runs construction from term selection through the hearing and the appeal, and routes each stage to the Marksy documents that do the work. It explains why the intrinsic record dominates and how disclaimer and lexicography actually operate, why proposing twelve terms signals that the case-deciding one has not been identified, and how to test a proposed construction against both the infringement and the invalidity positions before committing to it. It covers means-plus-function claiming and indefiniteness, expert declarations and their limits, the joint statement and the briefing, the tutorial, and the consistency problem across parallel forums. It closes with the reading path, the authorities table, and the forms.

IP and Technology > Patent Litigation | Toolkit | Published 29 June 2026 - Updated 21 July 2026 | Casey Scott McKay - marksy.us

Summary. Claim construction decides more patent cases than any other event, and it is decided almost entirely on documents written years earlier by people who were not thinking about litigation. This toolkit runs construction from term selection through the hearing and the appeal, and routes each stage to the Marksy documents that do the work. It explains why the intrinsic record dominates and how disclaimer and lexicography actually operate, why proposing twelve terms signals that the case-deciding one has not been identified, and how to test a proposed construction against both the infringement and the invalidity positions before committing to it. It covers means-plus-function claiming and indefiniteness, expert declarations and their limits, the joint statement and the briefing, the tutorial, and the consistency problem across parallel forums. It closes with the reading path, the authorities table, and the forms.

Keywords: claim construction · term selection · ordinary meaning · intrinsic evidence · specification · prosecution history · disclaimer · lexicography · extrinsic evidence · expert declarations · dictionaries · indefiniteness · means plus function · corresponding structure · plain and ordinary meaning · joint claim construction statement · markman briefing · tutorial · appellate review · consistency across forums

Start Here

Thackery Networks is four months from a construction hearing. Its counsel has proposed eleven terms for construction. The opposing side has proposed nine, six of which overlap. The court has said it will construe no more than eight.

Three problems follow, and they are the same three in nearly every case.

Nobody has identified which single term decides infringement, so the eleven proposals are a hedge rather than a strategy.

The construction that would win non-infringement on the most important term would also, on examination, read the claim onto a prior art reference — which would win invalidity and lose the ability to argue non-infringement, and nobody has checked whether the two positions are consistent.

And the file wrapper contains an argument the applicant made in 2016 distinguishing a reference, which the client's counsel has not read and which the other side has.

This toolkit answers three questions.

Which terms should be construed? The ones that decide infringement or validity. Everything else is noise that consumes the court's limited attention.
What does the record actually say? The claims, the specification, and the prosecution history, read in that order and read completely.
Does my construction work in both directions? A construction narrow enough to avoid the product may avoid the prior art; one broad enough to capture the product may capture it.

If you read only one thing, read What the Claim Means. It frames why this proceeding decides cases and what evidence actually moves it.

The Standard

Ordinary and customary meaning to a person of ordinary skill in the art at the time of the invention, read in light of the specification and the prosecution history.

The hierarchy. Intrinsic evidence first — the claims themselves, the specification, and the prosecution history. Extrinsic evidence — expert testimony, dictionaries, treatises, and inventor testimony — is secondary and cannot contradict a meaning the intrinsic record makes clear.

The claims inform each other. Differences between claims are presumed meaningful, and a limitation in a dependent claim is presumed absent from the independent claim it depends from. This is the most reliable tool in the entire exercise and it is underused.

The specification is the single best guide, and the tension is between reading the claims in light of it and importing limitations from it. A preferred embodiment does not limit a claim; a specification that describes the invention as always having a feature may.

The prosecution history shows what the applicant gave up. It is public, it is decisive more often than the specification, and it is the part that counsel most often has not read.

Terms not construed are given their plain and ordinary meaning, which is itself a construction and which a party may want.

Term Selection

Propose only terms that decide something. Infringement or validity. A term whose construction changes nothing is a term the court will resent construing.

Work backward from the contested element. Identify the claim limitation the case turns on, and construe the words in it that carry the dispute.

Test each candidate. If the term is construed my way, do I win? If it is construed their way, do I lose? A term that fails both tests should be dropped.

Expect a limit. Courts routinely cap the number of terms, and a party proposing eleven will have eight chosen for it — probably not the eight it would have picked.

Do not propose a term to preserve an argument. Preservation is not a reason and the argument will be diluted by the ones around it.

Watch the preamble. A preamble that gives life and meaning to the claim, or supplies antecedent basis, is limiting; one that merely states a purpose is not. This is worth resolving where the accused product falls outside the preamble's field.

Watch for terms of degree. "Substantially," "about," "approximately." Not automatically indefinite, and they require the specification to supply some objective boundary.

Watch for functional language, which may trigger means-plus-function treatment even without the word "means."

Reading the Intrinsic Record

Read every claim, not just the asserted ones. Claim differentiation arguments come from the unasserted ones.

Read the whole specification, including the background and the summary, and note every place the term appears.

Look for lexicography. A patentee may define a term, and doing so requires clear expression — "as used herein, X means" is the paradigm and clear intent expressed otherwise will also do.

Look for disavowal. A specification that distinguishes the invention from the prior art, or describes the present invention as always having a feature, or disparages an approach, can narrow the claims.

Read the entire file wrapper. Every office action, every response, every amendment, every interview summary, and every information disclosure statement.

Identify every amendment and its stated reason. A narrowing amendment for patentability limits the claim and surrenders equivalents in the territory given up.

Identify every argument distinguishing a reference. A clear statement that the invention differs from the art in a particular way constrains the claim as effectively as an amendment and leaves no trace in the claim language.

Read the parent and sibling files. A disclaimer made in a parent application carries to the children, and statements in a related application about a shared term are relevant.

Read the foreign counterparts where they exist, because arguments made abroad about the same term are extrinsic evidence and can be persuasive.

Building the Construction

State a construction, not a rejection. "Plain and ordinary meaning" is a position, and it is a weak one where the parties genuinely dispute what that meaning is. Courts increasingly require a party asserting plain meaning to say what it is.

Support each construction with intrinsic citations, by column and line. A construction supported only by expert testimony will lose to one supported by the specification.

Explain why the other side's construction is wrong on the intrinsic record rather than on consequences. "Their construction would mean we do not infringe" is not an argument about meaning.

Check the construction against the whole claim. A construction that renders another limitation superfluous is disfavored.

Check it against the dependent claims. A construction that reads a dependent claim's limitation into the independent claim violates claim differentiation.

Check it against the specification's embodiments. A construction excluding the preferred embodiment is rarely correct.

Check it against the prior art. This is the step that is skipped. A construction broad enough to capture the accused product may capture a reference, which trades a non-infringement position for an invalidity one.

Check it against every other forum where the same term is in issue, because the Board applies the same standard and a position taken there travels.

Means-Plus-Function and Indefiniteness

The trigger. 35 U.S.C. § 112(f) applies where a limitation is expressed as a means or step for performing a function without reciting sufficient structure. The word "means" creates a presumption; its absence creates the opposite presumption, and both are rebuttable.

Nonce words. "Module," "unit," "mechanism," "element," "device," and similar terms recited with a function and no structural content frequently trigger the provision.

The construction. The claim covers the structure described in the specification for performing the recited function, and equivalents. Identifying the corresponding structure is the whole exercise.

Computer-implemented functions. The corresponding structure is the algorithm disclosed for performing the function, not the processor that runs it. A specification that describes only a general-purpose computer discloses no structure and the claim is indefinite.

Indefiniteness generally. 35 U.S.C. § 112(b) requires the claims, read in light of the specification and prosecution history, to inform a skilled artisan about the scope with reasonable certainty. It is a question of law with underlying factual findings, and it is litigated alongside construction.

Why it is worth raising. An indefinite claim is invalid, which is a complete answer rather than a narrowing, and the analysis lives in the same record the construction briefing already assembles.

Experts, Dictionaries, and the Rest

Extrinsic evidence is secondary, and it cannot be used to vary a meaning the intrinsic record makes clear.

Where an expert helps. Establishing the level of ordinary skill, explaining what a term of art meant to a skilled artisan at the time, and explaining the technology so the court can read the specification.

Where an expert does not help. Offering a construction. An expert declaration that recites the party's proposed construction and calls it the ordinary meaning is given little weight, and it invites a deposition that undermines it.

Dictionaries. General-purpose dictionaries are weak; technical dictionaries and treatises contemporaneous with the filing are better. Neither overcomes the specification.

Inventor testimony about what the inventor meant is generally unhelpful, because the question is what a skilled artisan would understand from the document.

Prior art as extrinsic evidence. How a term was used in the art at the time can illuminate its ordinary meaning, and it is frequently more persuasive than any dictionary.

Depositions. Where the other side files an expert declaration, depose the declarant. The productive lines are what the expert relied on, whether they read the file wrapper, and whether the construction offered is derived from the intrinsic record or from the litigation position. Fed. R. Evid. 702.

The Procedure

The joint claim construction statement. Agreed constructions, disputed terms with each side's proposal, and the intrinsic support each relies on. Agreeing terms that do not matter is free and it concentrates the court's attention on the ones that do.

Briefing. Usually simultaneous opening briefs and simultaneous responses, sometimes sequential. Page limits are tight and they reward a party that proposed three terms over one that proposed eleven.

The technology tutorial. Frequently offered, sometimes required, and it is worth doing well. A judge who understands the technology reads the specification correctly, and a tutorial that argues rather than teaches damages the party giving it.

The hearing. Argument on each disputed term, with the court's questions being the whole of the useful information. Prepare for questions rather than for a presentation.

Live testimony is occasionally permitted and rarely necessary.

The order. May issue promptly or may take months, and it may adopt neither party's construction — which is a common outcome and a reason to have a fallback position.

After the order. Re-run the infringement charts against the adopted construction, reassess the invalidity contentions, and reassess settlement. This is the largest repricing event in most cases.

Consistency Across Forums

The same standard applies at the Board. Ordinary and customary meaning in light of the specification and prosecution history, which means a position taken in a petition or a patent owner response is a position taken in the district court.

The practical consequence. A patentee that narrows a term at the Board to avoid the art has narrowed it against its own infringement case. A petitioner that broadens a term to capture the art has broadened it against its own non-infringement case.

Prosecution of continuations creates the same problem. An argument made to an examiner in a pending sibling application is a statement about the shared term.

Foreign proceedings are not binding and are quotable.

The discipline. Maintain one construction position per term across every forum, decided by whoever is coordinating, and clear every filing that touches a construed term through that person.

Thackery's Three Problems

Eleven proposed terms. Identify the limitation that decides infringement, construe the words in it that carry the dispute, and drop the rest. Three well-supported constructions will get more attention than eleven, and the court's cap means the alternative is having eight chosen at random.

The construction that wins twice and loses once. Run the proposed construction against the prior art before committing. Where a construction that avoids the product also reads on a reference, the party has to choose between non-infringement and invalidity — and choosing deliberately is far better than discovering the conflict in a reply brief.

The 2016 argument. Read the file wrapper, completely, before proposing anything. An argument distinguishing a reference is a disclaimer that constrains the claim with no trace in the claim language, and the other side has already found it. Counsel that proposes a construction inconsistent with its own client's prosecution statements has produced the strongest exhibit in the other side's brief.

The Canons, and What They Are Worth

Practitioners cite construction canons as though they were rules. They are tendencies, they conflict, and knowing their relative weight is most of the craft.

Claim differentiation. A limitation in a dependent claim is presumed absent from the independent claim. Strong, reliable, and the most useful tool available — but it is a presumption that yields to a clear specification or prosecution statement.

The specification is the single best guide. Weighty, and it runs directly against the next canon.

Do not import limitations from the specification. Equally weighty. The reconciliation is that a preferred embodiment does not limit, while a specification describing the invention as always having a feature may. Where these two collide, the outcome turns on how uniformly the specification presents the feature.

Prosecution disclaimer. Very strong where the statement is clear and unmistakable, and unavailable where it is ambiguous. This is the canon that most often decides a close case.

Lexicography. Absolute where the patentee clearly defined a term, and clarity is required — an implicit definition inferred from usage rarely suffices.

Claims should be construed to preserve validity. Weak, disfavored, and invoked constantly by patentees. It applies only where the claim is genuinely ambiguous after all other tools, which is rarely.

Avoid rendering a limitation superfluous. Reliable, and it is worth checking against every proposed construction.

Consistency across a family. A term construed in one patent should carry the same meaning in a sibling sharing the specification.

Ordinary meaning governs absent a reason. The default, and a party asserting it should still say what it is. 35 U.S.C. § 112(b) requires the claims to inform a skilled artisan of the scope, which means a term with no ascertainable ordinary meaning is a candidate for indefiniteness rather than a candidate for plain meaning.

Building the Record Before Litigation

Construction is decided on documents written during prosecution, which means the most consequential claim construction work happens years before any complaint.

Every argument distinguishing a reference is a future disclaimer. Say what the rejection requires and stop. 37 C.F.R. § 1.111.

Every amendment surrenders equivalents in the territory given up, which is why amendments should be drawn to the art rather than to comfort.

Interview summaries are part of the record, and a carelessly written one reads as an admission. 37 C.F.R. § 1.133.

Consistency across a family matters. A statement about a shared term in one application constrains the siblings, and prosecution counsel handling several members separately produce inconsistencies nobody intended.

Define terms deliberately or not at all. Lexicography is powerful and it must be clear. A specification that uses a term loosely across several passages invites an argument that it was defined in a way the patentee did not intend.

Describe the invention in terms that do not overclaim uniformity. "In one embodiment" is safer than "the present invention," and specifications that repeatedly say the latter supply disavowal arguments.

Support the claims literally. Under 35 U.S.C. § 112(a) the specification must describe and enable what is claimed, and a construction that the specification does not support is a construction that produces an invalidity finding rather than an infringement one.

Keep a construction file per family — the point of novelty, the amendments and their reasons, the arguments that could read as disclaimers, and the terms most likely to be disputed. That page is what makes construction analysis take an afternoon rather than a week, and it is written best by the person who prosecuted the application.

After the Order

The construction order is the largest repricing event in most patent cases, and what happens in the two weeks after it determines a great deal.

Re-run every infringement chart against the adopted construction, element by element. A construction that neither party proposed — a common outcome — may create infringement where the patentee did not claim it or eliminate it where the defendant did not expect.

Re-run the invalidity contentions. A broadened construction may capture prior art that was previously irrelevant, and the invalidity case may be stronger than it was the week before.

Reassess the equivalents position. The construction changes what literal infringement means, which changes what the equivalents theory has to reach — and the prosecution history estoppel analysis has to be redone against the adopted meaning.

Move to amend contentions if the construction changed the theory. Courts frequently permit amendment following a construction neither party proposed, and the motion should be filed within weeks rather than months.

Reassess the expert reports that have been drafted or served, because a report built on a rejected construction is a report that will be excluded or discredited.

Move for summary judgment where the construction resolved it. The all-elements rule means one element decides it, and a construction that eliminates one element is a motion. Fed. R. Civ. P. 56.

Reassess settlement immediately. Both sides now know the answer to the central question, and the number moves accordingly. A party that waits a month to reprice has given the other side a month to do it first.

Consider the interlocutory posture. Construction is not ordinarily appealable before final judgment, and a party that lost decisively sometimes stipulates to judgment on the adopted construction in order to take the appeal. This is a deliberate strategy and it requires care in how the stipulation is drafted so the appellate issue is preserved cleanly. 35 U.S.C. § 141.

Appeal

The standard. Construction is reviewed without deference as to the intrinsic record. Subsidiary factual findings based on extrinsic evidence are reviewed for clear error, which is why a party relying on expert testimony to establish ordinary meaning is building a record that is harder to overturn — and harder to defend.

What this means strategically. A construction argued and won on the intrinsic record is vulnerable on appeal, because the appellate court will read the same documents afresh. One won on a factual finding about what a skilled artisan understood is more durable and it requires building that record deliberately at the hearing.

Preserve the alternative constructions. A party that proposed one construction and lost has no fallback; one that proposed a primary and an alternative has something to argue.

Preserve the indefiniteness argument separately, because it is a distinct ground with a distinct standard and it survives even where the construction dispute is lost.

Watch the interaction with the parallel proceeding. A Board decision on a construed term, and any appeal from it, can reach the appellate court on a different schedule and produce a controlling determination for the district court case.

And expect a remand. A reversed construction sends the case back for reconsideration of infringement, validity, and damages against the new meaning, which is a substantial fraction of the work done again — and it is the reason construction deserves the attention this toolkit gives it.

A Worked Construction

A claim recites "a controller configured to allocate a buffer prior to receipt of the first data packet." Three words are disputed: controller, allocate, and prior to receipt.

Controller. The defendant argues it is a means-plus-function limitation because "controller" is a nonce word recited with a function. The specification describes a microprocessor executing firmware and includes a flowchart of the allocation routine. The patentee argues "controller" is a term of art with structural meaning in the field, supported by a contemporaneous technical dictionary and by the specification's use of it alongside other structural components. Outcome: the presumption against means-plus-function applies where "means" is absent, and a term with recognized structural meaning in the art rebuts the defendant's argument. But the patentee's fallback matters — if the court treats it as means-plus-function, the flowchart supplies the algorithm and the claim is definite rather than indefinite. 35 U.S.C. § 112(f).

Allocate. Not defined in the specification and used consistently. Neither side's construction changes the infringement analysis. Agree it and spend the court's attention elsewhere.

Prior to receipt. The term the case turns on. The accused product allocates on receipt of the first packet, not before. The defendant proposes "before any portion of the first data packet arrives at the controller." The patentee proposes "before processing of the first data packet begins."

The intrinsic record decides it. The specification describes the advantage as avoiding a delay that occurs when allocation happens during processing — which supports the patentee. The file wrapper, however, contains a response distinguishing a reference on the ground that the reference "allocates memory only after the packet has arrived, whereas the present invention allocates in advance of arrival." That is a clear statement about arrival rather than about processing, made to obtain allowance, and it is prosecution disclaimer.

The outcome. The defendant's construction is adopted, and non-infringement follows on summary judgment under the all-elements rule. The patentee's counsel had not read the 2016 response.

The lesson. Two of the three terms did not matter. The third was decided by a sentence in a file wrapper that was public from the day the patent issued, and the party that read it won.

Working the Hearing

The hearing is short and it is the only opportunity to hear what the court is actually thinking.

Prepare for questions, not for a presentation. The court has read the briefs. What it wants is help with the two or three points it finds difficult, and a party that delivers a prepared argument instead of answering them has wasted the appearance.

Know the record cold. Column and line for every supporting passage, page and line for every prosecution statement. A judge who asks where the specification says that and receives an immediate citation is a judge who trusts the rest of the argument.

Lead with the strongest term and be prepared to be interrupted.

Concede what should be conceded. A party that defends every proposed construction with equal vigor loses credibility on the one that matters. Agreeing to the other side's construction of a term that does not change the outcome buys attention for the one that does.

Have a fallback. Courts frequently adopt neither party's proposal, and counsel who can respond usefully to "what if I construed it this way" is participating in the drafting of the order.

Bring the demonstratives the tutorial used, so the technology explanation and the construction argument use the same vocabulary.

Do not argue infringement. Construction is about meaning, and a party that argues consequences signals that its position on meaning is weak.

Take notes on the questions. They are the best available forecast of the order, and they inform whether to prepare a summary judgment motion or a settlement position while waiting.

Ten Failure Modes

Proposing terms as a hedge. Eleven proposals mean the case-deciding term was never identified, and the court's cap will choose eight of them at random.

Asserting plain and ordinary meaning without saying what it is. Increasingly treated as no position at all.

Not reading the file wrapper. The most common and most consequential omission, and the other side has read it.

Not reading the parent and sibling files, where a disclaimer made in a parent carries to the children.

Building a construction on expert testimony that the intrinsic record contradicts.

An expert declaration that recites the proposed construction and calls it the ordinary meaning, which is given little weight and invites a damaging deposition. Fed. R. Evid. 702.

Not testing the construction against the prior art, so a position that wins non-infringement turns out to win invalidity instead.

Inconsistency with a position taken at the Board, where the same standard applies and the filings are public.

A construction that renders a limitation superfluous, or that reads a dependent claim's limitation into the independent claim.

No fallback position, so a court inclined to adopt neither proposal has nothing from your side to work with.

And one that is not a failure. Losing a construction and having preserved a clean appellate record on the intrinsic evidence, because that review is without deference and it is where a substantial share of these determinations are corrected. 35 U.S.C. § 141.

The Two-Week Preparation

Before proposing a single term, two weeks of reading produces better results than two months of briefing.

Week one, the record. Every claim in the patent, asserted or not. The whole specification. The complete file wrapper, including the parent and siblings. Every foreign counterpart's prosecution where one exists. And the accused product's technical documentation.

Week one, the output. A list of every claim term the case could plausibly turn on, and for each, the intrinsic support for both readings.

Week two, the testing. Each candidate construction run against infringement, against the prior art, against the dependent claims, against the specification's embodiments, and against any position the client has taken in another forum.

Week two, the output. Three terms, each with a primary construction, an alternative, intrinsic citations by column and line, and a one-paragraph explanation of why the other side's reading fails on the record rather than on consequences.

Everything else follows from those two weeks. The joint statement, the briefing, the tutorial, the hearing, and the post-order reassessment are all execution against a position that was either correctly identified in week one or was not.

A Suggested Reading Path

Before proposing terms:

To connect construction to the merits:

For the disclosure grounds that travel with it:

Primary Authorities

| Authority | Proposition | |---|---| | 35 U.S.C. § 112 | Definiteness; means-plus-function | | 35 U.S.C. § 101 | Eligibility; construction affects the analysis | | 35 U.S.C. § 102 | Novelty; construction against the art | | 35 U.S.C. § 103 | Obviousness | | 35 U.S.C. § 271 | Infringement; construction against the product | | 35 U.S.C. § 282 | Presumption of validity | | 35 U.S.C. § 122 | Publication; the file wrapper is public | | 35 U.S.C. § 132 | Office actions; the prosecution record | | 35 U.S.C. § 141 | Appeal; review of construction | | 35 U.S.C. § 311 | Inter partes review; the same standard | | 37 C.F.R. § 1.75 | Claim form; dependency | | 37 C.F.R. § 1.111 | Reply; where disclaimers are made | | 37 C.F.R. § 1.133 | Interviews; the summary as record | | Fed. R. Civ. P. 56 | Summary judgment following construction | | Fed. R. Evid. 702 | Expert testimony on ordinary meaning |

Forms and Templates

The Office Action Response Template belongs here rather than only in a prosecution toolkit, because the responses drafted under it are the documents that will be construed. Counsel drafting a response should write it knowing that every argument distinguishing a reference is a disclaimer and every amendment surrenders equivalents. The Portfolio Inventory Template should carry, for each family, the one-sentence claim scope and a note of any known disclaimers — which is the field that makes a construction analysis take an afternoon rather than a week. The License Agreement Template matters because a construction adopted in litigation defines the scope of every licence under the patent afterward. The Cease and Desist Template is worth reading with construction in mind, because a letter that characterizes a claim's scope is a statement a defendant will quote.

Related Toolkits and Checklists

For the case around it, the Patent Litigation Toolkit supplies the sequence and the decision points. For the parallel proceeding applying the same standard, the PTAB Practice Toolkit covers the consistency problem. For the damages consequences of a narrowed construction, the Patent Damages and Remedies Toolkit. For the record that construction reads, the Patent Prosecution Toolkit explains how it was written. And for the doctrine underneath, the Patent Fundamentals Toolkit.