Claim Charts book

Claim Charts: Marshaling Facts in Patent Litigation

by Andrew Schulman (Software Litigation Consulting)

Draft material from forthcoming book

This is a work in progress. Citations are largely absent, and will be until completion of the first draft. The author welcomes comments and criticisms.

Also see 6-part introduction to software patent litigation, and excerpts from claim-charts book published on LinkedIn, more-recently-updated than the material below:


Claim charts perform a major role in patent litigation. Also known as claims tables, infringement contentions (ICs), and invalidity contentions, with those presented early in litigation often referred to as initial or preliminary infringement contentions (PICs), claim charts are required under the Local Patent Rules (LPRs) adapted in most federal district courts, and would be mandated under some proposed amendments to the federal patent statute.

As the term is used here, claim charts compare patent claims with something outside the patent (extrinsic evidence), and are distinctly different from claim-construction charts, in which (as with claim construction generally) intrinsic evidence is strongly favored over extrinsic evidence.

Though the focus of many published opinions for example in N.D. Cal. and E.D. Tex., the creation of, and best practices for, claim charts otherwise remain largely uncodified. This relative lack of published attention to claim charts is based in part on the seemingly self-explanatory nature of a two-column table whose basic grid is easily created in a word processor, with the left column’s contents dictated by the claims of a patent, and with the right column filled in with facts regarding an extrinsic practice of each element or step of a patent claim.

Many patent litigation attorneys view claim charts as merely a tiresome chore to be got through. Though required under the LPRs, ICs are not intended to prove a party’s case, and may therefore be seen as little more than obligatory notice to the other side. It will be shown that claim charts have a major goal, apart from notice, which is to lock-down case theories.

Claim charts further appear to raise no doctrinally-interesting issues; in the words of one attorney, “what’s the big deal, you just compare the claim to whatever thing you say infringes or invalidates the patent.” This is consistent with a general tendency to regard the marshaling of facts in patent litigation as largely unproblematic, at least in contrast to thorny issues of law. As a partial example, even the superb Patent Litigation casebook by Moore et al. devotes a single page to literal infringement, which is the workhorse of patent litigation, but dozens of pages to the prosecution history estoppel carve-out to the doctrine of equivalents.

An in-depth look at claim charts will show that the comparison of patent claims on the one hand, with materials outside the four corners of the patent on the other, has its own complexities, and that these complexities are revealing of larger issues. While invalidity charts generally focus on the well-established practice of comparing patent claims with published prior art, infringement contentions compare patent claims with items lifted out of the “real world”: actual products, devices, services and methods. Indeed, as the defense of invalidity is most successful when presenting prior art not already considered by a patent examiner, and as patent examiners generally depend on readily-accessible published prior art, invalidity contentions too often require a comparison of patent text with real-world non-textual embodiments. Comparing two texts is often difficult enough; aligning, or showing lack of alignment between, text and non-text materials (or quasi-text such as computer software) is more so, or at least more problematic than the scant attention to claim charts would suggest.

Some important aspects of this type of patent matching are nicely illustrated using computer software, in particular source code, and while drawing on case law regarding claim charts from a wide variety of technology, this study of claim charts is informed by the author’s experience in software patent litigation. In part because source code is arguably made up of the same raw material (text written according to certain rules) as the patent claims themselves, software patent claim charts help establish some subtle points for example regarding the naming of components or steps, and about the pinpointing of locations within devices or methods.

While this book refers throughout to claim “charts” and “tables,” it does not fetishize the two-column format, and most of the material herein is equally applicable to any document, whether employing a table or not, in which patent claims are split into limitations and compared on a limitation-by-limitation basis with something outside the four corners of the patent.

In showing that claim charts are more complex than seems at first glance, the goal here is not the production of lengthy, complicated charts. Courts frown on overdone charts, just as on overlong briefs, and the sheer size of some claims charts suggests, not solidity, but desperation or lack of commitment to a case theory —  and, as will be seen, forcing early commitment to case theories is largely the intent behind the claim-charts requirement. An important goal here is using the process of creating the chart as a tool to work through thorny factual issues.

Apart from its immediate application to patent litigation, an in-depth look at claim charts also serves as a case study in “heightened pleading,” the shift in civil litigation from mere notice (whose most extreme exemplar was unlamented Form 18) to a “plausibility” standard (Iqbal, Twombly, In re Bill of Lading), and partial shifts from discovery to mandatory disclosures (claim charts were intended largely to replace contention interrogatories), and from discovery to pleading.

Finally, it will be seen that the narrow topic of claim charts — i.e., aligning patent claims with real-world exemplars or non-exemplars — casts light on larger areas involving the alignment of known models or standards with items found “in the field”; the comparison of textual and non-textual material; and, more broadly, the intersection of facts and law. As one example, forensic matching, such as tool-mark examination or document examination, involves many of the same issues of feature and pattern recognition as do the factual aspects of patent litigation (whether this tool made this mark seems particularly close to whether this patented invention was used in this product/service/method). Neither forensic comparisons nor claim charts are a “holistic” exercise, but instead require the selection of specific elements or features or attributes along which to perform a series of individual comparisons, and a determination of how those individual comparisons fit together into a conclusion.

Roadmap to the book

The first section introduces the subject of claim charts; poses and answers a set of who/what/when/where questions about claim charts; describes their underlying purposes and policy goals; summarizes claim-chart requirements common to the many different Local Patent Rules and highlights some important or interesting district-specific rules; covers the application of the Federal Rules of Civil Procedure to claim charts; and discusses the results of not meeting the requirements.

The next section (Part II) covers the different types of claim charts, and scenarios in which claim charts are used, including not only the most common —  infringement contentions (ICs), initial or preliminary infringement contentions (PICs), and invalidity contentions — but also domestic industry (DI) charts employed in International Trade Commission (ITC) importation actions; three-column charts incorporating claim construction; claim charts for design patents; expert charts; “limitation charts” sometimes used when litigating multiple patents with overlapping limitations; and several other types. Special material within a claim claim, including doctrine of equivalents (DoE), means-plus-function, and obviousness, are also covered here.

The next section (Part III) is perhaps the most immediately hands-on, covering drafting claim charts, including overall formatting, how patent claims are split into individual rows of the chart (more than merely splitting the claim along its semicolon-designated “seams”); finding limitations and sublimitations of the claim; identifying non-limiting clauses; determining what goes into the right-hand column of the chart; handling dependent claims; and the subject of omissions (both what should or should not be omitted from the chart, and negative claims).

This is followed by Part IV, with coverage of chart “specificity”: the LPRs and cases mean by “specificity” not the mere accumulation of lots of specific details, but rather a factual analog to legal “pinpoint” citations; making assertions of infringement or invalidity and showing evidence for these assertions; “weaving” that evidence with the claim limitations; specifying locations where claim limitations are found, or not found, in the item under comparison; providing proper names for locations, parts, and steps; and being sufficiently specific about accused products and types of infringement. The section discusses computer source-code as an example of one type of evidence frequently used in the right column of claim charts.

Up to this point, we have largely assumed a single asserted patent, a single accused product or piece of prior art, a single defendant, and a single claim construction. The “multiplicity problem” or “quantity case” section (Part V) brings in multiple claims, patents, products, alternate claim constructions (claim charts often must be prepared before a definitive Markman ruling). This section also discusses proposed responses to abusive quantity, not only by plaintiffs, but also by defendants.

The section on analyzing, responding to, and offensively using the other side’s charts (Part VI) includes critically analyzing/assessing one’s own charts by asking oneself a series of who/what/where/why/how/how much questions, and turning around to critically analyze the other side’s charts; deciding how to respond to perceived deficiencies in the other side’s charts; and offensively using the other side’s charts, for example by mining differences between a party’s infringement and validity charts.

The next section (Part VII), on common claim-chart problems, enumerates many problems identified by the courts, including conclusory charts, “mimicking” charts (which merely ape the claim language rather than truly analyzing the accused product), merely exemplary charts, charts which merely juxtapose (without explanation or even assertion) facts with claim language, overdone charts, and so on.

The final section (Part VIII) covers several important topics, including amending and supplementing charts; the interaction between claim charts and experts (including expert reports doing the work of claim charts, whether or not in tabular format); the interaction between remedies (damages and injunctive relief) and claim charts; some underlying concepts such as “embodiment” which logically could have been discussed earlier but whose significance would likely not be clear until this point; and a conclusion on claim charts as a case study in the comparison of samples and exemplars (forensic matching), text and non-text, and facts and law.






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