Patent Damages Checklist: A Practical Checklist

Summary. Every damages task, in the order it has to happen.

Phase 1 — Pre-filing audit (patentee)

• Identify every accused product and model number.
• Estimate accused units and revenue for the full period from public sources.
• Fix the six-year boundary under 35 U.S.C. § 286 and delete everything earlier.
• Determine whether asserted claims include apparatus claims, triggering marking.
• Audit marking on your own products practicing an apparatus claim.
• Audit marking on every licensee's products. Obtain samples or photographs.
• If virtual marking is used, confirm the web page is live, freely accessible, and current.
• If marking is deficient, identify the earliest defensible actual notice date.
• Confirm any notice letter identified the patent number and the accused product.
• Consider asserting method claims to avoid the marking requirement entirely.
• Inventory every license to the patent or its family, with rates and structures.
• Inventory every valuation of the patent prepared for any purpose.
• Assess whether you practice the invention (lost profits available) or only license it.
• Identify acceptable non-infringing substitutes that a defendant will raise.
• Identify the smallest salable patent-practicing unit.
• Assess whether any entire-market-value theory is credible.
• Assess willfulness evidence: notice, copying, internal documents.
• Estimate fee exposure in both directions under 35 U.S.C. § 285.
• Apply a gauntlet discount for claim construction, IPR, summary judgment, trial, and appeal.
• Write the valuation down. Share it with the client.

Failure mode: discovering an unmarked licensee product during expert discovery, after three years of damages have been built into the client's expectations.

Phase 2 — Pre-response audit (accused infringer)

• Identify every accused product and confirm which the plaintiff has actually accused.
• Compute the § 286 boundary independently.
• Demand marking evidence in the first document requests.
• Identify unmarked products sold by the patentee or any licensee.
• Evaluate whether the notice letter, if any, was legally sufficient.
• Identify all licenses the company holds in the field — these are often the best damages evidence available.
• Preserve and collect the non-infringing alternatives record before engineers leave.
• Identify competitor products that were commercially available during the period.
• Collect design-around studies, including abandoned projects.
• Audit the knowledge file: every internal document referencing the patent or patentee.
• Decide, with the client, whether an opinion of counsel will be relied on, and understand the privilege waiver.
• Confirm that under 35 U.S.C. § 298 the absence of an opinion cannot be used to prove willfulness.
• Assess § 101, § 102, § 103, and § 112 challenges — invalidity is the cheapest damages defense.
• Evaluate whether an inter partes review under 35 U.S.C. § 311 is available and timely.

Phase 3 — Discovery

• Negotiate native production of transactional financial data in the ESI protocol at the Rule 26(f) conference.
• Request unit sales and revenue by product, by month, for the full period.
• Request customer-level data if lost profits or market share are in play.
• Request cost build-ups sufficient to compute incremental margin.
• Request pricing histories, discounts, and rebates.
• Request all licenses in the field, taken or granted.
• Send third-party confidentiality notices required by those licenses, early.
• Confirm a protective order is in place before license production.
• Request marketing materials describing the accused feature.
• Request win/loss analyses, competitive intelligence, and customer requests.
• Request product roadmaps and business cases mentioning the accused feature.
• Request all documents concerning knowledge of the patent (willfulness).
• Request design-around analyses and non-infringing alternative studies.
• Depose a corporate witness on financial data structure and accounting policies.
• Depose a corporate witness on marking practices.

Failure mode: 40,000 pages of PDF sales reports that cost more to rebuild than the analysis is worth.

Phase 4 — Building the theory

For lost profits, confirm each Panduit element:

• Demand for the patented product — sales by either party.
• Absence of acceptable non-infringing substitutes — the element that decides the issue.
• Capacity to have made the sales — plant utilization, workforce, supply chain.
• Profit that would have been made — incremental, not gross, margin.
• Consider market share apportionment where competitors exist.
• Consider price erosion, and account for the volume that would have been lost at higher prices.
• Consider convoyed sales, and confirm functional relationship rather than mere co-sale.

For reasonable royalty:

• Fix the hypothetical negotiation date — when infringement began.
• Identify the smallest salable patent-practicing unit.
• If proposing a larger base, document the entire-market-value showing.
• Apportion within the base for unpatented features.
• Tie the apportionment fraction to technical testimony about contribution over the prior art.
• Derive the rate from comparable licenses, with each adjustment explained.
• Address the Georgia-Pacific factors that matter; explain why others do not.
• Sanity-check the result against the infringer's margin.
• Confirm no double counting between lost profits and royalty units.

Phase 5 — Expert management

• Search the expert's Daubert history and read every opinion.
• Provide the expert with native data, not counsel summaries.
• Hold a technical tutorial for the damages expert before opinions form.
• Confirm the damages expert's apportionment fraction is supported by the technical expert.
• Run an internal exclusion exercise before the report is served.
• Confirm the report addresses claim constructions as issued.
• Confirm the report complies with Rule 26(a)(2) disclosure requirements.
• Prepare the expert to reproduce every calculation orally.

Phase 6 — Reviewing the opposing report

• Reproduce every calculation from the inputs.
• Trace every factual citation to the underlying document.
• List every assumption and test its sensitivity.
• Test the base against apportionment law.
• Test the apportionment fraction for evidentiary support.
• Confirm the negotiation date.
• Test each comparable license for genuine comparability and explained adjustments.
• Check for double counting.
• Check the damages period against § 286 and the marking analysis.
• Write a two-page exclusion memo ranking the defects.

Phase 7 — Rule 702 practice

• Organize the motion around specific defects, not general unreliability.
• Request the right relief: full exclusion, partial exclusion, or limitation of the base.
• Address the 2023 amendment to Federal Rule of Evidence 702 expressly.
• Support each ground with deposition testimony, not just the report.
• If opposing, distinguish weight from admissibility with a clean methodological story.
• Consider a motion in limine to exclude whole-product revenue figures from the courtroom.

Phase 8 — Trial

• Prepare a visual showing the product, the smallest salable unit, and the patented contribution.
• Prepare the expert for cross on every adjustment.
• Prepare answers at multiple assumptions rather than one point estimate.
• Confirm the verdict form separates lost profits, royalty, and willfulness.
• Confirm jury instructions state the apportionment requirement.
• Decide whether to seek bifurcation of damages or willfulness.
• Move under Rule 50 on damages at the close of evidence and renew after verdict.
• Address sealing of financial exhibits with document-specific justification.

Phase 9 — Post-trial and remedies

• Brief enhancement under 35 U.S.C. § 284 and the Read factors after Halo.
• Brief fees under 35 U.S.C. § 285 and Octane Fitness.
• Seek prejudgment interest; brief rate and compounding.
• Confirm post-judgment interest under 28 U.S.C. § 1961.
• Brief the permanent injunction under 35 U.S.C. § 283 and the eBay factors.
• If the injunction is denied, brief or negotiate an ongoing royalty, expecting a rate above the jury's.
• Confirm all damages arguments were preserved for appeal.

Quick reference: what kills a damages case

Related documents

• Patent Damages: Reasonable Royalties, Lost Profits, Apportionment, and Enhancement
• Proving and Attacking Patent Damages: A Practical Guide
• Patent Damages Toolkit: Royalty Models, Expert Reports, and Daubert Motions
• Claim Construction Checklist: A Practical Checklist
• Patent Marking Compliance: A Practical Checklist
• Expert Disclosure and Daubert Challenge Checklist: A Practical Checklist
• Patent Litigation Toolkit: A Roadmap and Research Guide