Claim Charts

A patent claim chart is a structured document that maps each element (limitation) of a patent claim to corresponding features of an accused product, process, or prior art reference. Each row represents one claim limitation, with columns showing the claim language and the corresponding feature of the accused product or reference. Claim charts are the primary analytical tool in patent infringement analysis — they force a systematic, element-by-element comparison that reveals which limitations are clearly met, which may require doctrine of equivalents analysis, and which might be absent entirely. Courts require this analysis because patent infringement requires every limitation of the claim to be present in the accused product.

Claim charts serve multiple litigation functions: (1) COMPLAINT — a well-drafted complaint may include claim charts or a claim-by-claim allegations section to plead infringement plausibly under the Twombly/Iqbal standard (some districts require charts with the complaint); (2) INFRINGEMENT CONTENTIONS — virtually all district courts require detailed infringement contentions, usually in a claim chart format, within the first months of litigation; (3) EXPERT REPORTS — damages and infringement experts prepare detailed claim charts as part of their expert reports; (4) CLAIM CONSTRUCTION BRIEFS — claim charts help illustrate why a particular claim construction is correct or incorrect; (5) SUMMARY JUDGMENT — parties submit claim charts as evidence supporting or opposing summary judgment on infringement; (6) LICENSING — claim charts support licensing demand letters and negotiation by demonstrating why a product reads on specific claims.

Element-by-element analysis compares each limitation in the claim separately to the accused product or prior art. Patent infringement (literal) requires that the accused product or process contain every element of the claim — missing even one element means no infringement of that claim (the 'all elements rule'). The analysis proceeds: (1) identify the claim's elements/limitations; (2) construe each element using the Markman process (intrinsic evidence first — claims, specification, prosecution history); (3) compare each construed element to the accused product's features (evidence: product documentation, source code, technical specs, reverse engineering); (4) document whether each element is literally present, present under the doctrine of equivalents (function/way/result test), or absent.

A LITERAL INFRINGEMENT CHART shows how each claim element is directly, textually present in the accused product — the product literally has the exact thing the claim requires. A DOCTRINE OF EQUIVALENTS (DOE) chart shows that even though an element is not literally present, the accused product has an equivalent that performs substantially the same function, in substantially the same way, to achieve substantially the same result (the function-way-result test from Graver Tank). DOE analysis is conducted element-by-element — the equivalence must be established for each individual element, not the claim as a whole. Prosecution history estoppel limits DOE — if the applicant narrowed a limitation by amendment or argument, DOE cannot recapture the surrendered scope for that element.

Invalidity claim charts map prior art references (patents, publications, products) to claim elements to show anticipation (every element present in a single reference) or obviousness (elements distributed across multiple references with a motivation to combine). Invalidity claim charts follow the same element-by-element format but show the prior art disclosure rather than an accused product. For anticipation, the chart must show that a single reference discloses every limitation; for obviousness, a chart may use multiple columns for different references plus a motivation-to-combine column. These charts are used in IPR petitions, ex parte reexamination requests, and district court invalidity contentions.